Question

Given: KLMN is a parallelogram,

KA
− angle bisector of ∠K

LA
− angle bisector of ∠L
Prove: m∠KAL = 90°

Answer 1

wuts the answer its not sum of angles theorem but its 180 º and either

Complementary angles, consecutive angles of parallelogram supplementary, or exterior angles theorem.

Explanation:

Answer 2

sum of two adjacent angles of parallelogram is 180

so angle K + angle L = 180

as AK bisects angle K and LA bisects angle L

so, angle AKL + angle ALK = 180 /2 = 90

in triangle AKL,

angle AKL + angle ALK+angle KAL = 180(sum of all angles in triangle = 180)

so, from above two equations,

angle KAL = 90