Adjacent Angles of Parallelogram

Area of Parallelogram	Opposite Angles of Parallelogram	Adjacent Angles of Parallelogram	Diagonal Of Parallelogram	Difference & Similarity between Rectangle & Parallelogram
Difference & Similarity between Square & Parallelogram	Difference & Similarity between Square, Rectangle & Parallelogram	Properties of Parallelogram

Adjacent Angles in a parallelogram are always supplementary In other words, we can say: Sum of Adjacent Angles in a parallelogram is always equal to 180 degree. Example 1: Observe the parallelogram PQRS Since we know that sum of adjacent angles in a parallelogram is always equal to 180 degree, so we get: Angle P + Angle Q = 180 degree Angle Q + Angle R = 180 degree Angle R + Angle S = 180 degree Angle S + Angle P = 180 degree Example 2: In the given parallelogram ABCD, angle D = 70 degree. Find measure of the remaining angles. Solution: In the given parallelogram, Angle D = 70 degree Since, Adjacent Angles in a parallelogram are always supplementary, so we get: Angle D + Angle C = 180 degree Put the values of angle D from above and we get: 70 + Angle C = 180 Subtract 70 from both sides and we get: Angle C = 110 degree ..... (Statement 1) Now again from adjacent angle property of parallelogram we get: Angle C + Angle B = 180 degree Put the values of angle C from above statement 1 and we get: 110 + Angle B = 180 Subtract 110 from both sides and we get: Angle B = 70 degree ..... (Statement 2) Lastly, again apply adjacent angle property of parallelogram and we get: Angle B + Angle A = 180 degree Put the values of angle B from above statement 2 and we get: 70 + Angle A = 180 Subtract 70 from both sides and we get: Angle A = 110 degree