# Thread: analytic geometry

1. ## analytic geometry

i need to find the distance between these two points on a graph (1,3) and (-2,7)

its a multiple choise question and the options are, sqrt of 5, 25,7 and 5

soely on instinct, i beleive the awnser is 7, but i don't actuallyk now the formula to check it. so any help would be much appreciated.

2. Call the points $\displaystyle (a, b)$ and $\displaystyle (c, d)$.

The distance between the points is simply $\displaystyle \sqrt{(c-a)^2+(d-b)^2}$.

This is just pythagoras, making a right angle triangle and finding the lenght of the hypotenuse.

Hope this helps

Craig

3. Originally Posted by 14041471
i need to find the distance between these two points on a graph (1,3) and (-2,7)

its a multiple choise question and the options are, sqrt of 5, 25,7 and 5

soely on instinct, i beleive the awnser is 7, but i don't actuallyk now the formula to check it. so any help would be much appreciated.
USe the distance formula: sqrt{(x2-x1)^2+(y2-y1)^2}
sqrt{(-2-1)^2+(7-3)^2}
sqrr{9+16)
5: the answer is 5