Cumulative Exam Review

A student uses the equation [tex]\tan \theta=\frac{s^2}{49}[/tex] to represent the speed, [tex]s[/tex], in feet per second, of a toy car driving around a circular track having an angle of incline [tex]\theta[/tex], where [tex]\sin \theta=\frac{1}{2}[/tex]. To solve the problem, the student used the given value [tex]\sin \theta[/tex] to find the value of [tex]\tan \theta[/tex] and then substituted the value of [tex]\tan \theta[/tex] in the equation above to solve for [tex]s[/tex].

What is the approximate value of [tex]s[/tex], the speed of the car in feet per second?

A. 5.3
B. 7.5
C. 9.2
D. 28.3



Answer :

To determine the approximate value of [tex]\( s \)[/tex], the speed of the car in feet per second, we can follow a detailed step-by-step process based on the given conditions.

1. Given Information:
- The equation to find the speed is [tex]\(\tan \theta = \frac{s^2}{49}\)[/tex].
- The sine of the angle [tex]\(\theta\)[/tex] is given as [tex]\(\sin \theta = \frac{1}{2}\)[/tex].

2. Step 1: Calculate [tex]\(\theta\)[/tex]:
We know that [tex]\(\sin \theta = \frac{1}{2}\)[/tex]. Using the inverse sine function (arcsine), we find:
[tex]\[ \theta = \arcsin \left( \frac{1}{2} \right) \][/tex]
The value of [tex]\(\theta\)[/tex] in radians is approximately [tex]\(0.5236\)[/tex].

3. Step 2: Calculate [tex]\(\tan \theta\)[/tex]:
Using the calculated value of [tex]\(\theta\)[/tex], we now find [tex]\(\tan \theta\)[/tex]:
[tex]\[ \tan(0.5236) \approx 0.5774 \][/tex]

4. Step 3: Substitute [tex]\(\tan \theta\)[/tex] into the equation [tex]\(\tan \theta = \frac{s^2}{49}\)[/tex]:
We substitute [tex]\(0.5774\)[/tex] into the equation:
[tex]\[ 0.5774 = \frac{s^2}{49} \][/tex]

5. Step 4: Solve for [tex]\(s^2\)[/tex]:
Rearrange the equation to solve for [tex]\(s^2\)[/tex]:
[tex]\[ s^2 = 49 \times 0.5774 \approx 28.2902 \][/tex]

6. Step 5: Solve for [tex]\(s\)[/tex]:
Take the square root of [tex]\(28.2902\)[/tex] to find [tex]\(s\)[/tex]:
[tex]\[ s = \sqrt{28.2902} \approx 5.3188 \][/tex]

Therefore, the approximate value of [tex]\( s \)[/tex], the speed of the car in feet per second, is closest to [tex]\( 5.3 \)[/tex]. Hence, the correct answer is:

[tex]\[ \boxed{5.3} \][/tex]