Question

Which of the following options is INCORRECT?

• A. $\angle 1=\angle 3$
• B. $\angle 1+\angle 4+\angle 5={180}^o$
• C. $\angle 8=\angle 6$
• D. $\angle 1+\angle 3={180}^o$

Answer 1

The correct option is D $\angle 1+\angle 3={180}^o$

$\angle 1=\angle 2$ and $\angle 2=\angle 3$ (Alternate angles) ....(i)
So, $\angle 1=\angle 3$ .....From (i)

$\angle 1+\angle 4+\angle 5={180}^o$ .....(Angle sum property)
Also, $\angle 8=\angle 6$ (alternate angles)

$\angle 1+\angle 3={180}^o$ is not correct.

Hence, option D is correct.