∠ KAL = 90° (Proved)
Step-by-step explanation:
See the attached diagram.
As KLMN is a parallelogram, so ∠K + ∠ L = 180°
⇒ ............ (1)
Now, given that, and
So, ∠ AKL + ∠ ALK = 90° {From equation (1)}
Now, from Δ KAL, ∠ AKL + ∠ ALK + ∠ KAL = 180°
⇒ 90° + ∠ KAL = 180°
⇒ ∠ KAL = 90° (Proved)