Question

In the figure, the measure of $\angle B^{\prime }{A}^{\prime }{C}^{\prime }$ is

• A. ${50}^{\circ }$
• B. ${60}^{\circ }$
• C. ${70}^{\circ }$
• D. ${80}^{\circ }$

Answer 1

The correct option is B

${60}^{\circ }$

(b),

In the figure,

$\Delta ABC\cong \Delta A^{\prime }{B}^{\prime }{C}^{\prime }$

$\therefore \angle A=\angle A\Rightarrow 3x=2x+20$

$\Rightarrow 3x-2x=20\Rightarrow x=20$

$\angle B^{\prime }{A}^{\prime }{C}^{\prime }=2x+20=20\times 20+20$

$=40+20={60}^{\circ }$