# Ex.5.1 Q4 Lines and Angles - NCERT Maths Class 7

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## Question

Find the angle which is equal to its complement.

## Text Solution

What is known?

An angle which is equal to its complement.

What is the unknown?

Find measure of the angle.

Reasoning:

Let us say given angle is $$x$$ and according to the question, its complement angle will also be equal to $$x$$. The sum of angle and its complement angle is always equal to $$90^\circ.$$

Steps:

Solve for angle which is equal to its complement.

Let the angle be $$x$$.

Therefore, complement of this angle will also be $$x$$.

We know that, the sum of measure of pair of complementary angles is $$90^\circ.$$

$$x$$ + $$x$$ = $$90^\circ.$$

$$=>$$ 2$$x$$ = $$90^\circ.$$

$$=>$$ $$x = \frac{90^\circ} {2}.$$

$$=>$$ $$x$$ = $$45^\circ.$$

Thus, the angle which is equal to its complement is $$45^\circ.$$

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