Question

If triangle ABC is right angled at C then the value of Cos( A + B )is?

Answer 1

Answer:

cos90° = 0

Step-by-step explanation:

• as C is right angle, so , the summation of other angles are (180-90)=90
• A+B=90
• so, cos(A+B)=cos90°=0

Answer 2

Given:

A triangle ABC is right angled at C.

To find:

The value of Cos(A + B).

Solution:

To solve this question, first of all, we should know the angle sum property of a triangle which states that in a triangle ABC, the sum of all interior angles of the triangle ABC is equal to 180°.

This means,

angle A + angle B + angle C = 180°

So,

using the above property in a given triangle ABC we have,

angle A + angle B + angle C = 180°

angle A + angle B + 90° = 180°

angle A + angle B = 180° - 90°

angle A + angle B = 90°

So,

Cos(A + B) = Cos(90°) (from above)

Cos(A + B) = 0

[From trigonometric ratios, the value of Cos 90° = 0]

Hence, the value of Cos(A + B) is Cos(90°) = 0.