The corners of a triangle are at: D(-2, 1); E(-3, 5); (3, 6). What is the perimeter of the triangle?

1 Answer
Feb 14, 2018

See a solution process below:

Explanation:

To find the perimeter of the triangle we need to find the distance between the points:

D and E

E and F

F and D

The formula for calculating the distance between two points is:

#d = sqrt((color(red)(x_2) - color(blue)(x_1))^2 + (color(red)(y_2) - color(blue)(y_1))^2)#

Distance Between D and E

#d = sqrt((color(red)(-3) - color(blue)(-2))^2 + (color(red)(5) - color(blue)(1))^2)#

#d = sqrt((color(red)(-3) + color(blue)(2))^2 + (color(red)(5) - color(blue)(1))^2)#

#d = sqrt(-1^2 + 4^2)#

#d = sqrt(1 + 16)#

#d = sqrt(17)#

Distance Between E and F

The formula for calculating the distance between two points is:

#d = sqrt((color(red)(3) - color(blue)(-3))^2 + (color(red)(6) - color(blue)(5))^2)#

#d = sqrt((color(red)(3) + color(blue)(3))^2 + (color(red)(6) - color(blue)(5))^2)#

#d = sqrt(6^2 + 1^2)#

#d = sqrt(36 + 1)#

#d = sqrt(37)#

Distance Between F and D

#d = sqrt((color(red)(-2) - color(blue)(3))^2 + (color(red)(1) - color(blue)(6))^2)#

#d = sqrt(-5^2 + (-5)^2)#

#d = sqrt(25 + 25)#

#d = sqrt(25 xx 2)#

#d = sqrt(25)sqrt(2)#

#d = 5sqrt(2)#

Therefore the perimeter of the triangle is:

#sqrt(17) + sqrt(37) + 5sqrt(2)#

If the answer needs to be a number without radicals we have:

#4.123 + 6.083 + (5 xx 1.414) =>#

#4.123 + 6.083 + 7.070 =>#

#17.276# rounded to the nearest thousandth.