Question

Two angles are supplementary to each other. One angle is thrice the other. Find the angles.

• A. ${45}^o$
• B. ${50}^o$
• C. ${100}^o$
• D. ${135}^o$

Answer 1

Answer: (A), (D)

${135}^o$

Let the angles are $a$ and $b.$
$a$ and $b$ are supplementary angles.
$\therefore a+b={180}^o$

Given that one angle is thrice the other.
Let, $a=3b$
Substituting it in the above equation we get,
$3b+b={180}^o$
$\Rightarrow 4b={180}^o$
$\Rightarrow b=\frac{{180}^o}{4}={45}^o$
$\Rightarrow a=3b=3\times {45}^o={135}^o$