Ex.5.1 Q1 Lines and Angles Solution- NCERT Maths Class 7

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Question

Find the complement of each of the following

Text Solution

What is known?

Measure of angles.

What is the unknown?

Measure of complementary angles.

Reasoning:

The sum of complementary angles is always If the given angle is \(x\), then we can find complementary angle by subtracting from . Let us now find complement angles.

Steps:

i) Given angle \(=20^\circ\)

Complement angle of \(20^\circ\)

\[\begin{align}  &= 90^{\circ} -\text{[given angle]} \\ &=90^{\circ}- 20^{\circ} \\ &=70^{\circ} \end{align}\]

(ii) Given angle  \(= 63^\circ \)

Complement angle of \(63^\circ \) 

\[ \begin{align} &= 90^{\circ} -\text{[given angle]} \\ &= 90^{\circ}-63^{\circ} \\ &= 27^{\circ} \end{align} \]

(iii) Given angle  \(= 57^\circ\)

Complement angle of \(57^\circ\)

\[ \begin{align} &= 90^{\circ}- \text{[given angle]} \\ &= 90^{\circ}-57^{\circ} \\ &= 33^{\circ} \end{align} \]