SOLUTION: i need help with the following problem. textbook:0-13-187027-0 chapter 7.2 question 82 "find the equation of a hyperbola whose asymptotes are perpendicular." that's it. i

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: i need help with the following problem. textbook:0-13-187027-0 chapter 7.2 question 82 "find the equation of a hyperbola whose asymptotes are perpendicular." that's it. i      Log On


   



Question 114544: i need help with the following problem.
textbook:0-13-187027-0
chapter 7.2 question 82
"find the equation of a hyperbola whose asymptotes are perpendicular."
that's it. i've tried to figure it out but have been unable. any help would be greatly appreciated.
thanks

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Note: Remember, perpendicular lines can be found by multiplying the slopes. So if you had a slope of 1%2F2 and -2, you just multiply to get %281%2F2%29%28-2%29=-2%2F2=-1. Since the product is -1, the two lines are perpendicular.


Let's use the general equation of a hyperbola %28x-h%29%5E2%2Fa%5E2-%28y-k%29%5E2%2Fb%5E2=1
Remember, the asymptotes are simply equations of lines in the form of y=mx%2Bb. Also, their slopes m can be found by the ratio of a and b. In other words, m=b%2Fa or m=-b%2Fa. Now multiply these two slopes to get

%28b%2Fa%29%28-b%2Fa%29=-b%5E2%2Fa%5E2

Since the two asymptotes are perpendicular, their product is equal to -1. In other words, -b%5E2%2Fa%5E2=-1


-b%5E2=-a%5E2 Multiply both sides by a%5E2


b%5E2=a%5E2 Multiply both sides by -1 to get rid of the negatives


sqrt%28b%5E2%29=sqrt%28a%5E2%29 Take the square root of both sides


b=a

So this means that when a is equal to b, the two slopes are perpendicular


Now let a=1, then b=1 (you can pick any value). Now simply plug this into %28a-h%29%5E2%2Fa%5E2-%28y-k%29%5E2%2Fb%5E2=1 (note: I'm going to let h and k equal zero since they don't affect the solution)


a%5E2%2F1%5E2-y%5E2%2F1%5E2=1

which simplifies to

x%5E2-y%5E2=1


If we graphed this, we would get




and we can see that the asymptotes are the equations y=x and y=-x which are perpendicular.