Question

In the given figure, the points A, B, C, D are concyclic, when $x={80}^o$, if $z=y-20$ then $z=?$

• A. ${100}^o$
• B. ${80}^o$
• C. ${40}^o$
• D. ${140}^o$

Answer 1

The correct option is B ${80}^o$

If Quadrilateral ABCD is concyclic
Then,
Sum of opposites angles is $180$
$\therefore x+y=180$
$\Rightarrow$ $y=180-80$
$\Rightarrow$ $y=100$

Now,
$z=y-20$
$\Rightarrow$ $z=100-20$
$\Rightarrow$ $z=80$