Question

(4) (i) ABCD is a parallelogram. The ratio of ZA and ZB of this parallelogram is 5:4.
Find the measure of Z B.
Th
11​

Answer 1

Answer:

Let the common multiple of the given ratio then 

∴∠A=5x∘and∠B=4x∘

□ ABCD is a parallelogram.

∴∠A+∠B=180∘ [Adjacent angle of parallelogram are supplementary]

∴5x+4x=180∘

⇒9x=180∘

⇒x=180/9

⇒x=20∘

∠B=4x=4×20∘=80∘

The measure of ∠B is 80∘