The trigonometric ratios for the angles 30°, 45° and 60° can be calculated using two special triangles. An equilateral triangle with side lengths of 2 cm can be used to find exact values for ...

around a point add up to 360°. This fact can be used to calculate missing angles. \(c\) and \(30^\circ\) are called vertically opposite angles. Vertically opposite angles are equal.