Question

7. Two sides of a triangle are 8 cm and 5 cm and the perimeter of the triangle is 20 cm
Find the third side of the triangle.
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Answer 1

Answer:

Let the triangle be named ABC

so perimeter=AB+BC+CA

AB=8cm

BC=5cm

AC= Xcm

20=8+5+x

20=13+x

20-13=x

7=x

Therefore the third side is 7cm

Answer 2

Let the sides of the Triangle be = A, B and C

Given,

A= 8cm

B= 5cm

C=?

Given Perimeter= 20cm

Perimeter of Triangle= A+B+C=20

=>8+5+C=20

=>13+ C=20

=> C=20-13

=> C= 7 cm

Hence, the other side is 7cm