malory12
contestada

Tommy and Zach are starting out at the same position. Tommy runs north at 3 miles per hour and Zach starts to run east 2 hours later at the rate of 4 miles per hour. How long until Tommy and Zach are 8 miles apart?

Respuesta :

irspow
y=3(t+2), x=4t

By the Pythagorean Theorem

d^2=x^2+y^2  and using y and x from the beginning and 8^2 for d^2:

64=16t^2+(3t+6)^2

64=16t^2+9t^2+36t+36

64=25t^2+36t+36

25t^2+35t-28=0  I'll just use the quadratic equation as this has no nice integer solutions :)

t=(-35±√(4025))/50  and since t>0

t≈0.5689 hr (34:07  in minutes and seconds :P )

This is the time elapsed for Zach 




chul
Alright, so Tommy's rate is 3, and his time is at t+2.

The equation for that would be 3(t+2).

The distance in Zach is he is running at 4 miles per hour, only making his equation 4t.

They move at right angle to each other.

using Pythagorean theorem:

(6+3t)² + (4t)² = 8t²

36 + 36t + 9t² + 16t² = 64

25t² + 36t - 28 = 0

Use the quadratic formula

[tex] -b +/- \sqrt{ \frac{b^2-4a*c}{2a} } [/tex]

[tex] -36 +/- \sqrt{ \frac{1296+2800}{25} } [/tex]

t = 28/50

t = .56 hours, convert into minutes.

Your Answer:
33.6 minutes

Otras preguntas