# a pair of equal angles of rhombus has a measure of 30 degree less than the supplementry angle find the other pair of equal angles of the rhombus

When you know any 1 angle’s measure in a rhombus, you know all 4 angles’ measures. Opposite angles are congruent. And adjacent angles are supplementary - in other words any two adjacent angles sum to 180°. So if we have an angle that measures 60°, the other angles measure 120°, 60°, and 120°.

Now, since the diagonals of a rhombus bisect the pairs of opposite angles, each 120° angle is cut into two 60° angles by the shorter diagonal, forming 2 equilateral triangles within the rhombus, each sharing that shorter diagonal as one of its sides. So the shared side/ diagonal of the rhombus must be the same length as the 4 sides of the rhombus. And since we know the length of the rhombus’s sides is 10 cm, we know that the shorter diagonal is 10 cm as well.