Question

ΔABC is a right triangle where m∠B = 90°. The coordinates of A and B are (5, 0) and (2, 5), respectively. If the x-coordinate of point C is 7, what is the y-coordinate of C ?

A. 5
B. 7
C. 8
D. 10

Answer 1

you're given :
A = (5, 0)
B = (2, 5)

Answer 2

say
C = (7, y)

Answer 3

but how do you find the y coordinate?

Answer 4

use below :
product of slopes of perpendicular lines = -1

Answer 5

find the slope of AB
find the slope of BC

Answer 6

set the product equal to -1 and solve y

Answer 7

can you find the slopes ?

Answer 8

i knew how to do it before but i haven't done it in so long so i forgot how loll

Answer 9

easy, use the slope formula
http://www.algebra-class.com/image-files/slope-formula-2.gif

Answer 10

A = (5, 0)
B = (2, 5)

slope = ?

Answer 11

i got 5/-3 after i subtracted them. I think i did it wrong

Answer 12

Correct !

Answer 13

next, find the slope of BC

Answer 14

B = (2, 5)
C = (7, y)

slope = ?

Answer 15

im assuming you set the product of y=-1. So using that in the formula I got -6/5 for the slope

Answer 16

that comes later, first we need to find the slope in terms of y :

B = (2, 5)
C = (7, y)

slope = (y-5)/(7-2)
= (y-5)/5

Answer 17

now set the product of both slopes equal to -1 :

(5/-3)((y-5)/5) = -1

solve y

Answer 18

im thinking the slope is 8. Idk if i solved for y correctly or not

Answer 19

5 cancels out and you will get :

(y-5)/-3 = -1

y - 5 = 3
y= 8

Answer 20

good job !!!

Answer 21

lml i got it right ! :D

Answer 22

thank you ganeshie ur the besttt

Answer 23

no, you're the best !! yw :)