Question

please help as soon. as possible pls fast​

Answer 1

Step-by-step explanation:

cosA=4/5 then sinA=3/5

cosB=7/5√2 then sinB=1/5√2

sin(A+B)=sinA cosB+sinBcosA

=(3/5)*(7/5√2)+(1/5√2)*(4/5)

=21+4/25√2=25/25√2

=1/√2

sin(A+B)=1/√2

A+B=π/4

Answer 2

$\huge\bold{Question:-}$

If cos A =$\frac{4}{5} \: \: and \: \: \cos$B = $\frac{7}{5 \sqrt{2} }$

Prove that (A+B) $= \frac{\pi}{4}$

$\huge\bold{Used Formulae:-}$

Cos (A+B) = (CosA×CosB) - (SinA×SinB)

$45 \degree = \frac{\pi}{4}$

PROOF:-

Please refer to the attachments