Question

Find the sizes of the angles of a parallelogram if one angle is 20° less than twice the smallest angle.

Answer 1

let smallest angle be x°
then the other will be (2x-20)°
we know that adjacent angles of ||gm are supplementary
therefore,
x + 2x-20=180
3x=180+20
3x=200
x=200/3
x=66.6°
other angle =2× 66.6. -20= 113.3°

Answer 2

let one pair if opposite angle measure x and another  as y
.let y be smallest

therefore x=2y-20

and x+y=180 (in parallelogram sum of adjacent angles is 180)
2y-20+y=180
3y=200
y=66.66