Angles, lines and polygons - EdexcelAngles at a point and on a straight line

Polygons are multi-sided shapes with different properties. Shapes have symmetrical properties and some can tessellate.

Part ofMathsGeometry and measure

Angles at a point and on a straight line

Angles at a point

around a point add up to 360°. This fact can be used to calculate missing angles.

Example

Calculate angle \(a\).

360 degrees, split into 60, 95 and 105 degrees, plus unknown angle, a

\(a = 360 - 60 - 95 - 105 = 100^\circ\)

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 \(c\).

Intrersecting lines, showing known angle of 30 degrees, plus unknown angles, b and c

\(b = 180 - 30 = 150^\circ\)

\(c = 180 - 150 = 30^\circ\)

Notice that vertically opposite angles are equal.

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