In the given figure, ABCD is a parallelogram. If AM bisects ∠A and DM bisects ∠D, then ∠AMD = ____.
90°
Let ∠A=2x
Therefore, ∠D = 180° - 2x° (adjacent angles of a parallelogram are supplementary)
∠DAM = ∠MAB = x° (AM bisects ∠A) ……… (i)
∠ADM = ∠MDC
= 180°−2x°2 (AM bisects ∠D)
= 90° - x° ……… (ii)
In AMD,
∠DAM + ∠ADM + ∠AMD= 180° (sum of angles of a triangle)
x° + 90 - x + ∠AMD = 180°
∠AMD = 90°