Now the exam is bound to be identity conversion. The identity transformation uses the formula of two angles and the difference of two angles, and then the double angle. Generally, consider cosine multiple angle first, and construct it if it is not, such as 2cos? X is related to 2cos? x- 1

But this is different from before, so it will be+1 again.

Synchronize 2co? x- 1+ 1 = cos2x+ 1。

Remember, the topic is alive, the type is dead, and people are alive even more.

Then there is the test of the nature of the function, such as finding the monotonicity of the maximum value, but here you have to make clear the substitution of a whole, and the Asin(wx+t) in brackets should be regarded as a whole, because it is a whole linked to the sinX of the textbook.

Trigonometric functions generally take these tests. Solving triangles means using sine and cosine theorems. You can combine these two theorems, but they can definitely be solved. Trigonometric function is originally given points, but it depends on whether you use the formula carefully and flexibly enough. Doing more questions properly can improve your understanding ability.

Don't ask questions ~