Question

in ∆abc angle c is equal to 90° then find the value of Cos ( a + b)​

Answer 1

Answer:

cos(A+B)=0

Step-by-step explanation:

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

Answer 2

Since ABC is a right angled triangle right angled at C

Hence

A+B=180 ⁰

−C=90⁰

Hence

cos(A+B)

=cos(90⁰)

=0