Measure of opposite angles of parallelogram is always equal.
Example 1: Observe the following diagram of parallelogram ABCD:
Solution: In the above parallelogram ABCD:
Angle A = Angle B
Angle C = Angle D
Because opposite angles of parallelogram are equal.
Example 2: In the given parallelogram PQRS, Angle P = 50 degree and angle Q = 130 degree. Find the measure of remaining angles.
Solution: In the given parallelogram PQRS:
Angle P = 50 degree (given)
Angle Q = 130 degree (given)
As we know that opposite angles of parallelogram are equal, so we get:
Angle P = Angle R = 50 degree
Angle Q = Angle S = 130 degree
And we get the following resultant diagram:

