1、sin 30= 1/2。

2.sin 45= root number 2/2.

3.sin 60= root number 3/2.

Second, cos degree formula

1, cos 30= root number 3/2.

2, cos 45= root number 2/2.

3、cos 60= 1/2 .

Three. Sunlight formula

1, tan 30= root number 3/3.

2. Tan 45= 1.

3.tan 60= root number 3.

Properties of cosine theorem;

For any triangle, the square of any side is equal to the sum of the squares of the other two sides MINUS the product of the cosine of the angle between these two sides and them. If these three edges are A, B and C, then the property is satisfied:

A^2 = b^2+c^2-2nd century BC.

b^2 = a^2 + c^2 - 2 .

c^2 = a^2 + b^2 - 2 a b cosC .

cosC = (a^2 + b^2 - c^2) / (2 a b).

Cosb = (A 2+C 2-B 2)/(AD 2).

Cosa = (C 2+B 2-A 2)/(2 BC).