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Properties of Geometrical Figures, SM-Bank 015

The diagram below shows an isosceles triangle.
 

Determine the value of \(a^{\circ}\), giving reasons for your answer.   (2 marks)

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\(71^{\circ}\)

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\(\text{Isosceles triangle}\ \ \Rightarrow\ \ \text{angles opposite equal sides are equal}\)

\(2a^{\circ}\) \(=180-38\ \ \text{(180° in triangle)} \)  
\(a^{\circ}\) \(=\dfrac{142}{2}\)  
  \(=71^{\circ}\)