Junior high school, to cope with the exam: master the trigonometric function value of special angle.

First, master it skillfully.

Sine/Cosine/Tangent/Cosine (0,30,45,60,90)

Second: basic understanding (can be obtained by geometric methods)

( 15//75 ,22.5 //67.5 )

Third: (it can be found by geometric method)

( 18 //72 ,36 //54 )

PS:

At other times, you can look up the table (I don't know if the students still use it) or use a calculator.

attached drawing