Question

In the given figure, $a$ is greater than $b$ by two third of a right angle. The values of $a$ and $b$ are

• A. ${100}^{\circ },{80}^{\circ }$
• B. ${105}^{\circ },{75}^{\circ }$
• C. ${90}^{\circ },{90}^{\circ }$
• D. ${120}^{\circ },{60}^{\circ }$

Answer 1

Answer: (D)

${120}^{\circ },{60}^{\circ }$

Given a = b + $\frac{2}{3}\times {90}^{\circ }=b+{60}^{\circ }$

Also a + b = ${180}^{\circ }$ (linear pair)

$\Rightarrow b+{60}^{\circ }+b={180}^{\circ }$

$\Rightarrow 2b={120}^{\circ }$

$\Rightarrow b={60}^o\Rightarrow a={120}^o$