Question

if ABC is aright angled triangle right angled at C then value of cos (A+B ) is

Answer 1

Answer:

0

Step-by-step explanation:

In a right angle triangle ABC

C = 90 deg

Since in a triangle A + B + C = 180 deg

=> B + C = 90 deg

=> cos ( B + C ) = cos ( 90 deg ) = 0

Hope it helps

Answer 2

Given:

ABC is a right angled triangle and ∠C=90°

To Find:

Cos (A+B)=?

Solution:

In right ∆ ABC

∠A+ ∠B+ ∠C=180° [Sum angle property of a triangle ]

∠A+ ∠B+ 90°=180°

∠A+ ∠B=180°-90°

∠A+ ∠B=90°

∴ A+B=90°

Now

Cos(A+B)=Cos90°=0