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**Upper primary school mathematics question UPQ****107**

In the figure below, ABCD is a square. AFD and BCF are isosceles triangles. Find ∠ AFB.

Solution:

AFD is isosceles triangle

∠ DAF + ∠ ADF = 180^{0} – 72^{0} = 108^{0}

∠ DAF = ∠ ADF = 108^{0 } ÷ 2 = 54^{0}

ABCD is a square, ∠ DAB =∠ ABC = 90^{0}

∠ FAB = 90^{0} – 54^{0 }= 36^{0}

∠ ABF = 90^{0} – 20^{0} = 70^{0}

∠ AFB = 180^{0 }– 36^{0} – 70^{0} = 74^{0}