Q5 of 268 Page 4

Prove the following :

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

We know that






cos(90o) = 0


Taking LHS




= 0


Now, RHS = cos 90° = 0


∴ LHS =RHS


Hence, proved.


More from this chapter

All 268 →
5

Prove the following :

cos90° = 1 – 2 sin245° = 2cos245° – 1

 5

Prove the following :

sin30°.cos60° + cos30°.sin60° = sin90°

 5

Prove the following :

 5

Prove the following :