Two corners of an isosceles triangle are at (4 ,9 )(4,9) and (9 ,3 )(9,3). If the triangle's area is 64 64, what are the lengths of the triangle's sides?

1 Answer
Feb 11, 2016

enter image source here The sides are:
Base, b = bar(AB) = 7.8b=¯¯¯¯¯¯AB=7.8
Equal sides, bar(AC) = bar(BC) = 16.8 ¯¯¯¯¯¯AC=¯¯¯¯¯¯BC=16.8

Explanation:

A_Delta = 1/2 bh = 64
Using the distance formula find b...
b = sqrt((x_2-x_1)^2 + (y_2 - y_1)^2)
x_1 = 4; x_2 = 9; y_1 = 9; y_2 = 3
substitute and find h:
b = sqrt(25 + 36) = sqrt(61) ~~ 7.81
h = 2(64)/sqrt(61) = 16.4
Now using Pythagoras theorem find the sides, barAC:
barAC = sqrt(61/4 + 128^2/61) = sqrt((3,721 + 65,536)/2) = 16.8