Use the property of similarity of triangles =》the corresponding sides of a triangle should be in the same ratio.
Take the missing side as 'x'.
The corresponding sides here are,
■ 7 & 14 ft
■ 5 & x ft
7/14 = 5/x
7x = 5 × 14 (cross multiplication)
7x = 70
x = 70/7
x = 10 ft
Height of the tree = 10 ft.
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Hope it helps ⚜