Question

∆ and ∆DEF are congruent. If AB=7cm, BC=10 cm and DE= 2x-1, find the value of .

Answer 1

Answer:

In △ABC,

AB=AC=x and BC=10 cm

Draw a perpendicular from A on BC such that AD⊥BC

In an Isosceles triangle a perpendicular bisects the non- congruent side.

Hence, BD=21(10)=5 cm

In △ADB,

AB2=AD2+BD2

x2=AD2+52

AD=x2−25

Area of triangle = 21AD×BC

60=21(x2−25)(10)

12=x2−25

144=x2−25

x2=169

x=13 cm

Step-by-step explanation:

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