Question

Assertion (A): Sum of the pair of angles 120° and 60° is supplementary.

Reason (R): Two angles, the sum of whose measures is 180°, are called supplementary angles.

• A. Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
• B. Assertion (A) is true but reason (R) is false.
• C. Assertion (A) is false but reason (R) is true.
• D. Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).

Answer 1

The correct option is A Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).

We know that, pair of angles are said to be supplementary angles if their sum is equal to ${180}^{\circ }$.
Let, x be the supplement angle for ${120}^{\circ }$.
so,
${120}^{\circ }$+ $x$ = ${180}^{\circ }$
x = ${60}^{\circ }$

Therefore, Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).