Question

The supplementary angle of an angle which is equal to it's complement is __________.

• A. (45^\circ\)
• B. (135^\circ\)
• C. (90^\circ\)
• D. (75^\circ\)

Answer 1

The correct option is B (135^\circ\)

Let the angle equal to it's complement be angle x.
So, x + x = ${90}^{\circ }$
2x = ${90}^{\circ }$
x = ${45}^{\circ }$
Sum of supplementary angles = ${180}^{\circ }$
So, the required angle is ${180}^{\circ }$ - ${45}^{\circ }$ = ${135}^{\circ }$