1. given two right angles a and b, the formula can be used: tanA=a/b, A+B=90 degrees.

2. Given the right angle A and the hypotenuse C, you can use the formula: sinA=a/c, A+B=90 degrees.

The formula for calculating the acute angle of a right triangle is known.

Sina = BC/AB = 500/1000 =1/2.

So the angle A=30 degrees.

triangle

It is a closed figure composed of three line segments in the same plane but not on the same straight line, which has applications in mathematics and architecture.

Ordinary triangles are divided into ordinary triangles (three sides are unequal) and isosceles triangles (isosceles triangles with unequal waist and bottom and isosceles triangles with equal waist and bottom, that is, equilateral triangles); According to the angle, there are right triangle, acute triangle and obtuse triangle, among which acute triangle and obtuse triangle are collectively called oblique triangle.