Try some yourself
Find the unknown angles in each of these diagrams, which represent part of the bracing structure supporting a marquee.
(a) In ΔABC,
(b) In ΔFGH,
As EFG is a straight line,
Deduce the value of α in the triangle below.
Lines XY and XZ are of equal length. This means that the triangle is isosceles, so the base angles and are equal. Then
The third angle in the triangle is a right angle: .
Because the three angles in a triangle must add up to 180°,
Find the unknown angles in the following isosceles triangles, which represent roof rafters.
(a) As this is an isosceles triangle, α = β.
(b) As this is an isosceles triangle, γ = δ.