In the diagram, \(AB\) is parallel to \(DE\).
- On the diagram, label the alternate angles to \(a^{\circ}\) and \(b^{\circ}\). (1 mark)
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- Using part (a), show that the sum of internal angles of a triangle equals 180°. (2 marks)
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a.
b. \(DE\ \text{is a straight line.}\)
\(a^{\circ} + b^{\circ} + c^{\circ} = 180^{\circ}\ \ \text{(180° in a straight line)}\)
\(\therefore \ \text{Angle sum of}\ \Delta = a^{\circ} + b^{\circ} + c^{\circ} = 180^{\circ}\)
Show Worked Solution
a.
b. \(DE\ \text{is a straight line.}\)
\(a^{\circ} + b^{\circ} + c^{\circ} = 180^{\circ}\ \ \text{(180° in a straight line)}\)
\(\therefore \ \text{Angle sum of}\ \Delta = a^{\circ} + b^{\circ} + c^{\circ} = 180^{\circ}\)