# Right Angle

How to find the measure of the given angle by using the measure of a right angle: definition, 1 example, and its solution.

## Definition

A right angle is an angle

whose degree measure is 90.

Its symbol is [∟].

So if ∠A is a right angle,

then m∠A = 90.

## Example

Solution

Solution (Detail)

It says

the measure of the whole angle, m∠AOC, is 115.

So draw ∠AOC

and write 115º.

See the given angles.

The measure of the purple angle is [4x + 1].

The blue angle is a right angle.

So the measure of the blue angle is [90].

The purple angle and the blue angle

form the brown angle.

Its measure is [115].

So [4x + 1] + [90] = [115].

+1 + 90 = +91

Move +91 to the right side.

Then 4x = 24.

Divide both sides by 4.

Then x = 6.

So x = 6 is the answer.