The triangle below has a total perimeter of 450 cm.

(picture of a triangle with sides 128 and 150. Third side unknown)

Write an equation and solve it to find the length of the longest side of the triangle.

128x + 150 = 450; x = 2.34 cm

x + 278 = 450; x = 172 cm

2x + 278 = 450; x = 86 cm

150x + 128 = 450; x = 2.15 cm

Question

The triangle below has a total perimeter of 450 cm.

(picture of a triangle with sides 128 and 150. Third side unknown)

Write an equation and solve it to find the length of the longest side of the triangle.

 128x + 150 = 450; x = 2.34 cm

 x + 278 = 450; x = 172 cm

 2x + 278 = 450; x = 86 cm

 150x + 128 = 450; x = 2.15 cm

anonymous · Answer

Let the third side be x cm
hence 
Perimeter of the triangle = sum of all the sides
                       450 = 128 + 150 + x

i.e.    278+ x = 450 cm

i.e.   x= 450- 278 

i.e.    x= 172 cm