A sin 2 x cos x 1 cos x. N a m n m 3. Full video will be explained by Mandarin Chinese language.
2 1 n 2 n S a n d 11.
1 1 1 1 1 n n n a r a r s r r r. And also the pythagoras theorem which is very useful in solving trigonometry questions. A a am n m n 3. 1 1 d b a c a ad bc.