Question

The bisectors of any two adjacent angles of a parallelogram intersect at
(a) 40°
(b) 45°
(c) 60°
(d) 90°

Answer 1

(d) 90°

Explanation:
Sum of two adjacent angles = 180^o
Now, sum of angle bisectors of two adjacent angles = $\frac{1}{2}\times \left({180}^{\mathrm{o}}\right)={90}^{\mathrm{o}}$
∴ Intersection angle of bisectors of two adjacent angles = 180^o − 90^o = 90^o