http://www.usatestprep.com/modules/gallery/files/73/7362/7362.jpg

In parallelogram ABCD, find m∠A.
A)
15°
B)
70°
C)
110°
D)
200°

Question

http://www.usatestprep.com/modules/gallery/files/73/7362/7362.jpg

In parallelogram ABCD, find m∠A.
A)
15°	
B)
70°	
C)
110°	
D)
200°

mathstudent55 · Answer

If two parallel lines are cut by a transversal, then same-side interior angles are supplementary.
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mathstudent55 · Answer

m<1 + m<2 = 180

anonymous · Answer

oh okay. so would it be a.15?

anonymous · Answer

@mathstudent55

mathstudent55 · Answer

What is 15, the measure of angle A or x?

anonymous · Answer

the measure of angle a @mathstudent55

mathstudent55 · Answer

No, that can't be.
Since the two angles shown are same-side interior angles, they are supplementary.
The sum of their measures is 180.
You get this equation:
6x + 20 + 4x + 10 = 180
10x + 30 = 180
10x = 150
x = 15

mathstudent55 · Answer

Now that we have x = 15, we use the expression for the measure of angle A to find the actual measure of angle A:
m>A = 6x + 20 
         = 6(15) + 20
         = 90 + 20
         = 110

anonymous · Answer

oh okay that makes sense thankyou!

mathstudent55 · Answer

You're welcome.