Draw a line segment first, then aim a point in the middle of the protractor at an endpoint of the line segment to measure a 70-degree angle, and then point out a point opposite to the 70-degree angle at the edge of the protractor to connect the point with the endpoint.

For example:

1. It is possible to form an angle with the triangle so that ∠ BCA = 30.

2. Take any point p on the ruler and let it reach an endpoint o (the farthest edge of the ruler) with a length.

3. make a circle c with c as the center and a as the radius, so that CB and c intersect at B.

4. Let O move on a straight line AC and P move on the circumference of a circle C. When O, P and B are * * * lines, connect OB.

So ∠BOC is 1/3∠BCA= 10.

5. Make a 60-degree angle with a triangle and add them together.

Extended data:

In mathematics, radian is used instead of angle, because the divisibility of 360 is not important to mathematics, and radian is more convenient in mathematics. The relationship between angle and radian is: 2π radian = 360. Thus 1 ≈ 0.0 174533 radian, 1 radian ≈ 57.29578.

The formula for converting the angle into radian: radian = angle ÷ 180×π.

Formula for converting radian into angle: angle = radian×180÷π.

Baidu Encyclopedia-Angle