Respuesta :
According to the properties of parallelograms, two adjacent angles (A and B) are supplementary, i.e. they add up to 180 ° .
This means that
B+A=180, or using B=2A =>
2A+A=180
=>
3A=180
This means that
B+A=180, or using B=2A =>
2A+A=180
=>
3A=180
Let x be the measure of ∠A, so the measure of ∠B = 2x.
The equation is :
x + 2x = 180° ⇒ 3x = 180° ⇒ x = 180°:3 ⇒ x = 60°
So, m(∡A) = 60°.