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

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Find the complement of each of the following

 Video Solution
Lines & Angles
Ex 5.1 | Question 1

Text Solution

What is known?

Measure of angles.

What is the unknown?

Measure of complementary angles.


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.


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 \(57^\circ\)

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