Question

Triangle ABC and Triangle DEF and their area are respectively 49cm^2 and 100cm^2. If DE = 17.5cm , then find AB

Answer 1

Answer:AB=25

Step-by-step explanation: Area of triangle ABC ÷Area of DEF=DE^2÷AB^2

49÷100=17.5^2÷AB^2

49÷100=306.25÷AB^2

49AB^2=306.25×100 ( cross multiplication)

49AB^2=30625

AB^2=30625÷49

AB^2=625

AB=√625

Therefore, AB=25

Answer 2

$AB=12.25 cm$

Step-by-step explanation:

$\triangle$ABC$\sim\triangle$DEF

Area of triangle ABC=49 square cm

Area of triangle DEF=100 square cm

DE=17.5 cm

When two triangles ABC and DEF are similar  

Then, $\frac{ar(ABC}{ar(DE F)}=(\frac{AB}{DE})^2$

Using the formula  

$\frac{49}{100}=(\frac{AB}{17.5})^2$

$\frac{49}{100}=\frac{AB^2}{(17.5)^2}$

$AB^2=\frac{49\times (17.5)^2}{100}$

$AB=\sqrt{\frac{49\times (17.5)^2}{100}}$

$AB=12.25 cm$

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https://brainly.in/question/15207785:Answered by Tanikawaddle