Question

ABCD is a parallelogram. The ratio of angle A
and angle B of this
this parallelogram is 5:4. find the
the measure of angle B​

Answer 1

$\small\mathcal\red{Angle\:A=5x°}$

$\small\mathcal\red{Angle\:B=4x°}$

$\small\mathcal\purple{Adjacent\:angles\:of\: parallelogram\:are\: supplementary}$

$\small\mathcal\green{Angle\:A+Angle\:B=180°}$

$\small\mathcal\green{4x°+5x°=180°}$

$\small\mathcal\green{9x=180°}$

$\small\mathcal\green{x=\dfrac{180}{9}}$

$\small\mathcal\green{x=20°}$

$\small\mathcal\red{Value\:of\:x=20°}$

$\huge\mathcal\red{Angle\:B=}$

$\small\mathcal\red{4×20=80°}$