Question

For what value of x in the figure points A,B,C and D are concyclic?

• A. $9^{\circ }$
• B. ${10}^{\circ }$
• C. ${11}^{\circ }$
• D. ${12}^{\circ }$

Answer 1

Answer: (B)

${10}^{\circ }$

In the given figure

$\angle ABC+\angle ADC={180}^{\circ }$

$\Rightarrow {81}^{\circ }+x+{89}^{\circ }={180}^{\circ }$

$\Rightarrow x+{170}^{\circ }={180}^{\circ }$

$\Rightarrow x=180-170={10}^{\circ }$