Right Angled Triangle (Definition, Properties, Formulas) (2024)

A right-angled triangle is a triangle, that has one of its interior angles equal to 90 degrees or any one angle is a right angle. Therefore, this triangle is also called the right triangle or 90-degree triangle. The right triangle plays an important role in trigonometry. Let us learn more about this triangle in this article.

Table of Contents:
  • What is a Triangle
  • Types
  • Right Triangle
  • Shape
  • Properties
  • Area
  • Perimeter
  • Solved Examples
  • Practice Problems
  • FAQs

What is a Triangle?

A triangle is a regular polygon, with three sides and the sum of any two sides is always greater than the third side. This is a unique property of a triangle. In other words, it can be said that any closed figure with three sides and the sum of all the three internal angles is equal to 180°.

Right Angled Triangle (Definition, Properties, Formulas) (1)

Being a closed figure, a triangle can have different types and each shape is described by the angle made by any two adjacent sides.

Types of Triangles

Right Angled Triangle (Definition, Properties, Formulas) (2)

  1. Acute angle triangle:When the angle between any 2 sides is less than 90 degrees it is called an acute angle triangle.
  2. Right angle triangle:When the angle between a pair of sides is equal to 90 degrees it is called a right-angle triangle.
  3. Obtuse angle triangle: When the angle between a pair of sides is greater than 90 degrees it is called an obtuse angle triangle.

The other three types of triangles are based on the sides of the triangle.

  • Scalene triangle (All the three sides are unequal)
  • Isosceles triangle (Two sides are equal)
  • Equilateral triangle (All the three sides are equal)

Note: A scalene triangle and an isosceles triangle both can be a right triangle. A scalene right triangle will have all three sides unequal in length and any of the one angles will be a right angle. An isosceles right triangle will have its base and perpendicular sides equal in length, which includes the right angle. The third unequal side will be the hypotenuse.

Watch The Below Video To Learn More About the Types of Triangles

Right Angled Triangle (Definition, Properties, Formulas) (3)

Right Angled Triangle

A right-angled triangle is a type of triangle that has one of its angles equal to 90 degrees. The other two angles sum up to 90 degrees. The sides that include the right angle are perpendicular and the base of the triangle. The third side is called the hypotenuse, which is the longest side of all three sides.

The three sides of the right triangle are related to each other. This relationship is explained by Pythagoras theorem. According to this theorem, in a right triangle,

Hypotenuse2 = Perpendicular2 + Base2

See the figure below to understand better.

Right Angled Triangle (Definition, Properties, Formulas) (4)

The area of the biggest square is equal to the sum of the square of the two other small square areas. We can generate the Pythagoras theorem as the square of the length of the hypotenuse is equal to the sum of the length of squares of base and height.

Shape of Right Triangle

A right triangle is a three-sided closed shape, that has one perpendicular side called the leg or height of the triangle.

Right Angled Triangle (Definition, Properties, Formulas) (5)

Right Angle Triangle Properties

Let us discuss, the properties carried by a right-angle triangle.

  • One angle is always 90°or right angle.
  • The side opposite angle of 90°is the hypotenuse.
  • The hypotenuse is always the longest side.
  • The sum of the other two interior angles is equal to 90°.
  • The other two sides adjacent to the right angle are called base and perpendicular.
  • The area of the right-angle triangle is equal to half of the product of adjacent sides of the right angle, i.e.,

Area of Right Angle Triangle = ½ (Base × Perpendicular)

  • If we drop a perpendicular from the right angle to the hypotenuse, we will get three similar triangles.
  • If we draw a circumcircle that passes through all three vertices, then the radius of this circle is equal to half of the length of the hypotenuse.
  • If one of the angles is 90°and the other two angles are equal to 45°each, then the triangle is called an Isosceles Right Angled Triangle, where the adjacent sides to 90°are equal in length.

Above were the general properties of the Right angle triangle. The construction of the right angle triangle is also very easy. Keep learning with BYJU’S to get more such study materials related to different topics of Geometry and other subjective topics.

Area of Right Angled Triangle

The area is in the two-dimensional region and is measured in a square unit. It can be defined as the amount of space taken by the 2-dimensional object.

The area of a triangle can be calculated by 2 formulas:

\(\begin{array}{l}Area= \frac{a \times b }{2}\end{array} \)

And, Heron’s formula

\(\begin{array}{l}Area= \sqrt{s(s-a)(s-b)(s-c)}\end{array} \)

Right Angled Triangle (Definition, Properties, Formulas) (6)

Here, s is the semi perimeter and is calculated as:

\(\begin{array}{l}s =\frac{a+b+c}{2}\end{array} \)

Where, a, b, c are the sides of a triangle.

Let us calculate the area of a triangle using the figure given below.

Right Angled Triangle (Definition, Properties, Formulas) (7)

Fig 1: Let us drop a perpendicular to the base b in the given triangle.

Fig 2: Now let us attach another triangle to a side of the triangle. It forms the shape of a parallelogram as shown in the figure.

Fig 3: Let us move the red coloured triangle to the other side of the parallelogram as shown in the above figure.

Fig 4: It takes up the shape of a rectangle now.

Now by the property of area, it is calculated as the multiplication of any two sides

Hence, area =b × h (for a rectangle)

Therefore, the area of a right angle triangle will be half i.e.

\(\begin{array}{l}Area = \frac{b \times h}{2}\end{array} \)

For a right-angled triangle, the base is always perpendicular to the height. When the sides of the triangle are not given and only angles are given, the area of a right-angled triangle can be calculated by the given formula:

\(\begin{array}{l}Area = \frac{bc \times ba}{2}\end{array} \)

Right Angled Triangle (Definition, Properties, Formulas) (8)

Where a, b, c are respective angles of the right-angle triangle, with ∠b always being 90°.

Perimeter

As we know, the three sides of the right triangle are Base, Perpendicular and Hypotenuse. Thus the perimeter of the right triangle is the sum of all its three sides.

Perimeter of right triangle = Length of (Base + Perpendicular + Hypotenuse)

Example: If Base =4cm, Perpendicular= 3cm and Hypotenuse = 5cm. What is the perimeter of right triangle?

Perimeter = 4 + 3 + 5 = 12 cm

Solved Examples

Q.1: In a right triangle, if perpendicular = 8 cm and base = 6 cm, then what is the value of hypotenuse?

Solution: Given,

Perpendicular = 8 cm

Base = 6cm

We need to find the hypotenuse.

By Pythagoras theorem, we know that;

Hypotenuse = √(Perpendicular2 + Base2)

H = √(62 + 82)

= √36 + 64

= √100

= 10 cm

Therefore, the hypotenuse of the right triangle is 10 cm.

Q.2: If the hypotenuse is 13 cm and the base is 12 cm, then find the length of perpendicular of the right triangle?

Solution: Given,

Hypotenuse = 13 cm

Base = 12 cm

Perpendicular = ?

By Pythagoras theorem, we know that,

Hypotenuse2 = Perpendicular2 + Base2

Perpendicular2 = Hypotenuse2 – Base2

P = √(132 – 122)

P = √(169 – 144)

P = √25

P = 5 cm

Therefore, the value of perpendicular is 5cm.

Practice Problems

  1. Find the perpendicular length if a right triangle has a base of 2 units and a hypotenuse of √8 units.
  2. What is the area of the right triangle with a base of 7 cm and a hypotenuse of 25 cm?
  3. Show that in a right-angled triangle, the hypotenuse is the longest side.

To learn more interesting facts about triangles stay tuned with BYJU’S.

Frequently Asked Questions From Right Angle Triangle

Q1

What are Right Angled Triangles?

Right-angled triangles are those triangles in which one angle is 90 degrees. Since one angle is 90°, the sum of the other two angles will be 90°.

Q2

How to Find the Missing Side of any Right Angled Triangle?

For a right-angled triangle, trigonometric functions or the Pythagoras theorem can be used to find its missing sides. If two sides are given, the Pythagoras theorem can be used and when the measurement of one side and an angle is given, trigonometric functions like sine, cos, and tan can be used to find the missing side.

Q3

Can a Triangle have Two Right Angles? Explain.

No, a triangle can never have 2 right angles. A triangle has exactly 3 sides and the sum of interior angles sum up to 180°. So, if a triangle has two right angles, the third angle will have to be 0 degrees which means the third side will overlap with the other side. Thus, it is not possible to have a triangle with 2 right angles.

Q4

What is the sum of all the interior angles of the right triangle?

For any triangle, the sum of all the interior angles is equal to 180 degrees.

Q5

What are the three sides of the right triangle?

The three sides of a right triangle are base, perpendicular and hypotenuse.
What is the formula for a right-angled triangle?
We can use the Pythagoras theorem to find the sides of a right triangle.
C2 = A2 + B2

Right Angled Triangle (Definition, Properties, Formulas) (2024)

FAQs

Right Angled Triangle (Definition, Properties, Formulas)? ›

A right-angled triangle is a type of triangle that has one of its angles equal to 90 degrees. The other two angles sum up to 90 degrees. The sides that include the right angle are perpendicular and the base of the triangle. The third side is called the hypotenuse, which is the longest side of all three sides.

What is the definition and properties of a right-angle triangle? ›

Properties of Right - Angled Triangle

One angle of the triangle always measures 90degree. The hypotenuse is the longest side of the right-angle triangle. The side that is opposite to the 90degree angle is the hypotenuse. The Sum of two interior angles of the right-angled triangle is always 90degree.

What are the formulas for right angle triangles? ›

Right Triangles
  • Pythagorean theorem: a2 + b2 = c2.
  • Sines: sin A = a/c, sin B = b/c.
  • Cosines: cos A = b/c, cos B = a/c.
  • Tangents: tan A = a/b, tan B = b/a.

What is the formula for right angle properties? ›

What is the Formula for a Right-Angled Triangle? The formula which is used for a right-angled triangle is the Pythagoras theorem. It states that the square of the hypotenuse is equal to the sum of the squares of the other two sides. This means, (Hypotenuse)2 = (Base)2 + (Altitude)2.

What is the definition of a triangle in terms of properties and formulas? ›

A triangle has three sides, three angles, and three vertices. The sum of all internal angles of a triangle is always equal to 180°. This is called the angle sum property of a triangle. The sum of the length of any two sides of a triangle is greater than the length of the third side.

What is the formula for solving a right triangle? ›

The height of a right triangle can be calculated, given the length of base and height of a right triangle formula can be calculated using the Pythagoras theorem as, (Hypotenuse)2 = (Height)2 + (Base)2. Substitute the known values and solve for the height or perpendicular of the right triangle.

What are the formulas for triangles? ›

The two basic triangle formulas are the area of a triangle and the perimeter of a triangle formula. These triangle formulas can be mathematically expressed as; Area of triangle, A = [(½) base × height] Perimeter of a triangle, P = (a + b + c)

What is the formula for a right triangular? ›

In a right triangle with cathetus a and b and with hypotenuse c , Pythagoras' theorem states that: a² + b² = c² . To solve for c , take the square root of both sides to get c = √(b²+a²) . We can consider this extension of the Pythagorean theorem as a "hypotenuse formula".

What is the three special right triangles formula? ›

The special right triangle formulas in the form of ratios can be expressed as: 30° 60° 90° triangle formula: Short leg: Long leg : Hypotenuse = x: x√3: 2x. 45° 45° 90° triangle formula: Leg : Leg: Hypotenuse = x: x: x√2.

What is the definition of a right triangle in geometry? ›

A right-angled triangle is a type of triangle that has one of its angles equal to 90 degrees. The other two angles sum up to 90 degrees. The sides that include the right angle are perpendicular and the base of the triangle. The third side is called the hypotenuse, which is the longest side of all three sides.

What is the definition of right angle? ›

In geometry and trigonometry, a right angle is an angle of exactly 90 degrees or. 2 radians corresponding to a quarter turn. If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles.

What property is a right angle? ›

When two straight lines intersect each other at 90˚ or are perpendicular to each other at the intersection, they form the right angle.

Is sine opposite or adjacent? ›

Formulas for right triangles

If θ is one of the acute angles in a triangle, then the sine of theta is the ratio of the opposite side to the hypotenuse, the cosine is the ratio of the adjacent side to the hypotenuse, and the tangent is the ratio of the opposite side to the adjacent side.

What is the definition of a right angle in geometry? ›

In geometry and trigonometry, a right angle is an angle of exactly 90 degrees or. 2 radians corresponding to a quarter turn. If a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles.

Which of the following is the best definition of a right angle? ›

A right angle is an angle of 90°. When two rays intersect and form a 90˚ angle or are perpendicular to each other at the intersection, they are said to form a right angle.

Top Articles
Latest Posts
Article information

Author: Duncan Muller

Last Updated:

Views: 6359

Rating: 4.9 / 5 (59 voted)

Reviews: 82% of readers found this page helpful

Author information

Name: Duncan Muller

Birthday: 1997-01-13

Address: Apt. 505 914 Phillip Crossroad, O'Konborough, NV 62411

Phone: +8555305800947

Job: Construction Agent

Hobby: Shopping, Table tennis, Snowboarding, Rafting, Motor sports, Homebrewing, Taxidermy

Introduction: My name is Duncan Muller, I am a enchanting, good, gentle, modern, tasty, nice, elegant person who loves writing and wants to share my knowledge and understanding with you.