Question

ABCD is a parallelogram with AB parallel DC .if angle A =(5x+5) and angle B =(4x-5) find the value of x and the measure of all angles of the parallelogram ABCD.

Answer 1

sum of adjacent sides of //gm is 180

so,
  5x+5)+(4x-5)=180
  9x=180
  x=20
Angle A=5(20)+5=105
Angle B=75
Angle C=105
Angle D=75

Answer 2

since it is a llgm opposite angles will be equal
and also angle A+angle B+angle C+angle D=360
i.e., (5x+5)+(4x-5)+(5x+5)+(4x-5)=360
⇒5x+4x+5x+4x=360
⇒18x=360
⇒x=20
so the angels are,
Angle A=5(20)+5=105
Angle B=4(20)-5=75
Angle C=105
Angle D=75