Rajani wants to use a sheet of fiberboard 31 inches long to create a skateboard ramp with a 19° angle of elevation from the ground. How high will the ramp rise from the ground at its highest end? Round your answer to the nearest tenth of an inch if necessary.



Answer :

Let's solve the problem step-by-step to find the height of the ramp, also known as the rise, from the ground at its highest end:

1. Understand the Problem:
- We are given the length of the ramp (hypotenuse in a right triangle) as 31 inches.
- The angle of elevation from the ground is 19 degrees.
- We need to find the vertical rise (opposite side of the triangle) and round it to the nearest tenth of an inch.

2. Identify the Trigonometric Function to Use:
- Since we have the hypotenuse and we need to find the opposite side, we use the sine function. In a right triangle:
[tex]\[ \sin(\text{angle}) = \frac{\text{opposite}}{\text{hypotenuse}} \][/tex]

3. Set Up the Equation:
- Let [tex]\( \text{rise} \)[/tex] be the height of the ramp.
- Here, the sine function will be:
[tex]\[ \sin(19^\circ) = \frac{\text{rise}}{31} \][/tex]

4. Solve for Rise:
- Rearrange the formula to solve for the rise:
[tex]\[ \text{rise} = 31 \times \sin(19^\circ) \][/tex]

5. Calculate the Rise:
- Using a calculator, find [tex]\( \sin(19^\circ) \)[/tex].
- Multiplying the sine of 19 degrees by 31 will give:
[tex]\[ \text{rise} \approx 10.1 \][/tex]

6. Round the Result:
- The exact calculated rise is approximately 10.1 inches when rounded to the nearest tenth.

So, at its highest end, the ramp will rise approximately 10.1 inches from the ground.