Question 6b

Figure 1 shows Triangle ABC. BA = BC.Figure 2 shows the same triangle after it is folded along line DE.Find ∠y. (2 marks)

$Question 6b diagram$

Answer: 76 °

Workings

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∠ y = 180 - ∠ FAD (red) - ∠ FDA (blue)

since BA = BC, that makes BAC an isosceles triangle

∠ FAD = (180 - 84) ÷ 2 = 48

since ∠ EDC is 62 and folded, that means ∠ CDE is also 62

∠ FDA (blue) → 180 - 62 - 62 = 56

∠ y = 180 - ∠ FAD (red) - ∠ FDA (blue) = 180 - 48 - 56 = 76

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