In ΔABC, AB = 2√5 cm, AC = 10 cm, BC = 4√5 cm then ∠B is
A
120°
B
60°
C
90°
D
45°
Correct Option:
C
Explanation
For angle B, the opposite side is AC = 10 cm. AB² = (2√5)² = 20 and BC² = (4√5)² = 80. Thus AB² + BC² = 100 = AC². By the converse of Pythagoras' theorem, ∠B = 90°.
