Question

If ∆ABC us right angled at C, then the value of cos(A+B) is​

Answer 1

Answer:

0°

Step-by-step explanation:

Sum of all the angles = 180°

∠C = 90° ⇒ (A+B) = 90°

∴ cos(A+B) = cos90°

                  = 0

Answer 2

Step-by-step explanation:

$\bf\large\underline{Given~:}$

$~~~~~~~~~$• ∆ABC is right angled at C.

$\bf\large\underline{To~Find:}$

$~~~~~~~~~$•The value of cos(A + B).

$\bf\large\underline{Solution~:}$

Since , ∆ABC is right angled at C

∴ ∠C = 90°

:$\implies$A + B + C = 180

$~~~~~$:$\implies$A + B + 90

$~~~~~~~~~~$:$\implies$cos ( a + b ) = cos 90°

$~~~~~~~~~~~~~~~$:$\implies$${\underline{\boxed{\pink{\bf{cos ( a+ b ) = 0}}}}}$$\red\bigstar$