Q5 of 268 Page 4

Prove the following :
sin30°.cos60° + cos30°.sin60° = sin90°

We know that

sin (90^o) = 1

Taking LHS =

= 1

Now, RHS = sin 90° = 1

∴ LHS = RHS

Hence, proved.

Prove the following :

cos60° = 2cos²30° – 1 = 1 – 2 sin²30°

Prove the following :

cos90° = 1 – 2 sin²45° = 2cos²45° – 1

Prove the following :

cos60°.cos30° – sin60°. sin30° = cos 90°

Prove the following :

Prove the following :sin30°.cos60° + cos30°.sin60° = sin90°