Seventh grade mathematics geometry It is known that ∠α and ∠β are mutually complementary, and half of ∠β is 30 ° smaller than ∠α, so ∠α and ∠β can be calculated What about complementarity?

Seventh grade mathematics geometry It is known that ∠α and ∠β are mutually complementary, and half of ∠β is 30 ° smaller than ∠α, so ∠α and ∠β can be calculated What about complementarity?

The simultaneous equations of ∠α + ∠β = 90 ° and ∠α - ∠β / 2 = 30 ° are solved, and ∠α = 40 ° and ∠β = 50 ° are obtained
The simultaneous equations of ∠α + ∠β = 180 ° and ∠α - ∠β / 2 = 30 ° are solved, and ∠α = 80 ° and ∠β = 100 ° are obtained

Geometric formula of Mathematics
It's a square, a rectangle, a cube, a cuboid or something

Common junior high school mathematics formula 1 has and only has a straight line passing through two points 2 the shortest line segment between two points 3 the complementary angle of the same angle or equal angle is equal 4 the complementary angle of the same angle or equal angle 5 has and only has a straight line and a known straight line perpendicular to one point 6 of all line segments connected by a point outside the line and each point on the line, the vertical line segment is the shortest

A formula for calculating the side area

I didn't say what I wanted
Side area of the cylinder: S = π DH (D is the diameter of the bottom, h is the height)
I don't know if it's cylindrical. If it's not, please ask. If it's, remember to adopt it