Question

Let A = (0,0), B = (8,0), and C =(x,x). Find x, given that BC = 7

Answer 1

Use the distance formula


d = sqrt((x2-x1)^2+(y2-y1)^2)


7 = sqrt((x-8)^2+(x-0)^2)


7 = sqrt((x-8)^2+x^2)


7^2 = (x-8)^2+x^2


49 = (x-8)^2+x^2


49 = x^2-16x+64+x^2


49 = 2x^2-16x+64


0 = 2x^2-16x+64 - 49


2x^2-16x+15 = 0


I'll let you finish.

Answer 2

Alright that's what I did originally but when I factored 2x^2-16x+15 = 0 and got x = 4 +- srqt(17/2) I thought I did something wrong. Thanks

Answer 3

you should get

\[\Large x = \frac{8\pm\sqrt{34}}{2}\]

Answer 4

Ok I'll resolve this one