# Perimeter of an equilateral triangle

• Feb 8th 2011, 12:40 PM
Veronica1999
Perimeter of an equilateral triangle
The perimeter of an equilateral triangle exceeds the perimeter of a square by 1989cm. The length of each side of the triangle exceeds the length of each side of the square by d cm. The square has perimter greater than 0. How many positive integers are not possible values for d?

t for side of triangle s for side of square

3t = 4s + 1989

t - s = d

t= s +d

3s + 3d = 4s + 1989

3d = s + 1989
d = s/3 + 663

it doesn't seem to make sense.

Pls help.
• Feb 8th 2011, 01:06 PM
alexmahone
Quote:

Originally Posted by Veronica1999
The perimeter of an equilateral triangle exceeds the perimeter of a square by 1989cm. The length of each side of the triangle exceeds the length of each side of the square by d cm. The square has perimter greater than 0. How many positive integers are not possible values for d?

t for side of triangle s for side of square

3t = 4s + 1989

t - s = d

t= s +d

3s + 3d = 4s + 1989

3d = s + 1989
d = s/3 + 663

it doesn't seem to make sense.

Pls help.

$\displaystyle \displaystyle d=\frac{s}{3}+663$

$\displaystyle \displaystyle s>0 \implies d>663$

663 positive integers are not possible values for d. They are: 1, 2, 3, ... , 663.