kuCAu

2021-03-05

1. A curve is given by the following parametric equations. x = 20 cost, y = 10 sint. The parametric equations are used to represent the location of a car going around the racetrack. a) What is the cartesian equation that represents the race track the car is traveling on? b) What parametric equations would we use to make the car go 3 times faster on the same track? c) What parametric equations would we use to make the car go half as fast on the same track? d) What parametric equations and restrictions on t would we use to make the car go clockwise (reverse direction) and only half-way around on an interval of [0, 2?]? e) Convert the cartesian equation you found in part “a” into a polar equation? Plug it into Desmos to check your work. You must solve for “r”, so “r = ?”

liannemdh

Step 1 Answer for sub question a: Given x = 20 cos t, y = 10 sin t To find the cartesian equation that represents the race track the car is going on solve for t using the equation of y. $y=10\mathrm{sin}t$
$\frac{y}{10}\mathrm{sin}t$
$t={\mathrm{sin}}^{-1}\left(\frac{y}{10}\right)$ Further substitute the value of t in the equation of x. $x=20\mathrm{cos}\left({\mathrm{sin}}^{-1}\frac{y}{10}\right)$ Thus we have found the cartesian equation that represents the race track the car is going on. Step 2 Answer for sub question b: The parametric equations we would use to make the car go three times as faster on the same track is $x\left(t\right)=20cost\left(3t\right),y\left(t\right)=10sin\left(3t\right).$ Step 3 Answer for sub question c: The parametric equations we would use to make the car go half as fast on the same track is $x=20\mathrm{cos}\left(\frac{t}{2}\right),y=10\mathrm{sin}\left(\frac{t}{2}\right)$

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