Question

Please solve it... Its urgent

Answer 1

here is ur answer...

Answer 2

Question:-

Prove that

cos(A-B)= cosA.cosB+sinA.sinB if A=B =60°

Proof:-

Let us first put the vale of A and B in their places .

Given values of A and B are 60°&60°

So now put the values in RHS :-

cos60. cos60 + sin 60 . sin 60

= 1/2.1/2+ √3/2.√3/2

= 1/4+3/4

=(1+3)/4

=4/4 = 1

Now let us put the values of A & B in LHS :-

cos(A-B) = cos(60-60)

= cos0

We know that the value of cos 0 is 1 .

Hence LHS = RHS = 1

Hence proved LHS = RHS