Question 6

If area of similar triangles Δ ABC and Δ DEF be 64 sq cm and 121 sq cm and EF = 15.4 cm then BC equals:

Solution

Area of Δ ABC = 64 sq.cm
Area of Δ DEF = 121 sq.cm
Given that Δ ABC and Δ DEF are similar triangles.
Then, $$\dfrac{\text{Area of  } \triangle ABC}{\text{Area of  } \triangle DEF} = (\dfrac{BC}{EF})^2$$

=> $$\dfrac{64}{121} = (\dfrac{BC}{15.4})^2$$

=> $$\dfrac{BC}{15.4} = \dfrac{8}{11}$$

=> $$BC = \dfrac{8}{11}\times15.4 = 11.2 cm$$


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