Question

In quadrilateral ABCD, ∠A+∠C is 2 times of ∠B+∠D. If ∠A=140° and ∠D=60°, find ∠B.​

Answer 1

Answer:

let angle b+angle d=x

then angle c+ angle a=2x

x+2x=360

x=120

angle d=60

60+angle b=120

angle b=60

Answer 2

Answer:

A+C=2(B+D)

sum of all angles in a quadrilateral is 360

A+B+C+D=360

we know that A+C=2B+2D

2B+2D+B+D=360

3B+3D=360

B+D=120

we know D=60

60+B=120

B=120-60

therefore the answer is 60