Angles at a point and on a straight line
Angles at a point
An angle is formed when two straight lines meet. around a point add up to 360°. This fact can be used to calculate missing angles.
Example
Calculate angle \(a\).
\(a = 360^\circ - 60^\circ - 95^\circ - 105^\circ = 100^\circ\)
Angles on a straight line
Angles on a straight line add up to 180°. This fact can also be used to calculate angles.
Example
Calculate the angles \(b\) and \(c\).
\(b = 180^\circ - 30^\circ = 150^\circ\)
\(c = 180^\circ - 150^\circ = 30^\circ\)
\(c\) and \(30^\circ\) are called vertically opposite angles.
Vertically opposite angles are equal.