## anonymous one year ago Jimmy hits a baseball so that it travels at a speed of 110 ft/sec and at an angle of 35 degrees with the horizontal. Assume his bat contacts the ball at a height of 3.5 ft above the ground. Write a pair of parametric equations to simulate the path of the ball. -What is a parametric equation? -I know I need to draw a triangle, but where do I go from there? What does the speed mean?

1. anonymous

Parametric equation give x and y as functions of a third variable called the parameter (usually t). Once you draw the triangle, resolve the speed into vertical and horizontal vectors.

2. anonymous

The horizontal speed is constant at 110 cos 35°, so the horizontal path follows x = (110 cos 35°)t, where t = time.

3. anonymous

How do you know it's a cosine function?

4. anonymous

from the triangle|dw:1433813593966:dw|

5. anonymous

Vx = 110 cos 35° Vy = 110 sin 35°

6. anonymous

Oh, ok! That makes a lot more sense, thank you

7. anonymous

The vertical speed changes due to gravity, so use the physics/kinematics equation to model the distance. $y=-\frac{ 1 }{ 2 }at^2+v _{0}t+ y _{0}$ a = 32, v0 = 110 sin 35° y0 = 3.5

8. anonymous

Alrighty, that sounds good. Thank you so much!

9. anonymous

you're welcome