Question

In triangle ABC right angled at C, the value
of Cos (A+B) is​

Answer 1

Answer:

We know that the sum of all 3 angles in a triangle is 180° .

C=90°

But,

A+B+C=180°

⟹A+B=(180−90)°=90°

We also know that cos90°=0

Hence,

cos(A+B)=0

this is the correct solution

Answer 2

Answer:(AC+BC)/AB

Step-by-step explanation: Cos = Adjacent/Hypotenuse

CosA = AC/AB

CosB = BC/AB

Cos(A + B) = AC/AB + BC/AB = (AC+BC)/AB

Hope it helps!!