Question

If ∆ABC is right angle at C, find the value of cot(A+B)

Answer 1

SOLUTION:
GIVEN:
∠C = 90°
(A+B) + C = 180°
[sum of the interior angles of a triangle is 180° ]
(A+B) = 180° - ∠C
(A+B) = 180° - 90°
(A+B) = 90°
So, cos(A+B) = cos(90°)
cos(A+B) = 0
[Cos 90°= 0]
Hence, the value of cos(A +B) = 0

Cot (A+B)=cot 90=0