Question

Let A = 30° and B = 60°. Verify each of the
56. cos (A + B) = cos A cos B - sin
A sin B ​

Answer 1

Answer:

Step-by-step explanation:

We know that,

SinA=sin30=1/2

SinB=sin60=√3/2

CosA=Cos30=√3/2

CosB=Cos60=1/2

With these values in mind...

LHS

cos (A + B)

A = 30° and B = 60°

Therefore,

cos(30+60)

=cos90

=0

( because cos90=0)

RHS

cos A cos B - sinA sin B ​

Putting values,

= (√3/2*1/2) - (1/2*√3/2)

=0

Therefore, LHS = RHS

HENCE VERIFIED

Answer 2

Hello,

Here A is 30° and B is 60°

Show the equation is as follow,

56cos(A+B) = cosAcosB - sinAsinB

So LHS

56cos(30° + 60°)

56cos(90°)..................cos 90° is 0

56x0

0

RHS

CosAcosB - sinAsinB

Cos30°cos60° - sin30°sin60°

√3/2*1/2 - 1/2*√3/2............ (Cos30 is

√3/2 and sin 30 is 1/2 and vice versa for 60°)

√3/4 - √3/4

0

So LHS=RHS

Verified