Angles in a triangle add up to 180° and in quadrilaterals add up to 360°. Angles can be calculated inside semicircles and circles. Parallel lines in shapes can form corresponding and alternate angles.
Part ofMathsGeometry
For any triangle the 3 angles add up to \(180^\circ\)
\(x^\circ = 180^\circ - (70^\circ + 50^\circ )\)
\(= 180^\circ - 120^\circ = 60^\circ\)
An equilateral triangle is one with all 3 sides equal in length and all 3 angles equal to \(60^\circ\)
An isosceles triangle is one with two sides equal in length and two equal angles.
In the diagram below the triangle is isosceles. What is the value of \(a^\circ\)?
\(a^\circ = 180^\circ - (70^\circ + 70^\circ )\)
\(= 180^\circ - 140^\circ = 40^\circ\)