Angles
Angles – these are measurable in degrees (radians, etc.) geometric figures, including a vertex and a pair of rays emanating from it. They can be components of various flat and volumetric figures. Angles can be straight (180 degrees), straight (90 degrees), acute (less than 90) and obtuse (more than 90).
Equal angles are those angles that, when superimposed, show complete coincidence. Two angles can be called adjacent if they have one common side.
If two rays coincide, we can speak of an angle equal to 0 degrees. As one ray rotates, the size of the angle increases until the two rays coincide again. In this case, the angle is 360 degrees.
Angles are measured with a protractor, a tool with two scales, angular and linear, invented in ancient Babylon. In addition, a goniometer and a sextant were used to determine the ship's position at sea by measuring angles. The construction theodolite also uses the method of angle measurement. The biblical «Jacob's staff» served for astronomical observations.
Calculate, find angles of geometric figures
| Angles of a triangle find angles of a triangle knowing the side lengths | Angles of a right triangle find angles of a right triangle knowing the lengths of the legs |
| Angles of an isosceles triangle find angles of an isosceles triangle knowing the sides and base | Angles of a rhombus find angles of a rhombus knowing the diagonal and side length |
| Angles of a parallelogram find angles of a parallelogram knowing the side lengths and diagonal | Cotangent Table find the cotangent of an angle |
| Polygon find all angles of a regular polygon | Sine table find the angle of the sine |
| Cosine table find values of the cosine angle | Tangent Table find the tangent of an angle |