Question: Question 15
(a) For each triangle, find the ratio of the length of the side opposite 61.2° to the length of the hypotenuse. Round your answers to the nearest hundredth.
JK / JL =
PQ / PR =
XY / XZ =
(b) Use the ALEKS Calculator to find sin 61.2°, cos 61.2°, and tan 61.2°.
Round your answers to the nearest hundredth.
sin 61.2° =
cos 61.2° =
tan 61.2° =
(c) Which trigonometric function gives each ratio of sides in part (a)?
sine
cosine
tangent
none of these
1. **State the problem:**
We have three right triangles each with an angle of $61.2^\circ$. We need to find the ratio of the side opposite this angle to the hypotenuse for each triangle, then find the sine, cosine, and tangent of $61.2^\circ$, and finally identify which trigonometric function corresponds to the ratios found.
2. **Formula and rules:**
The sine of an angle in a right triangle is defined as:
$$\sin(\theta) = \frac{\text{opposite side}}{\text{hypotenuse}}$$
This means the ratio of the side opposite the angle to the hypotenuse is the sine of that angle.
3. **Calculate the ratios for each triangle:**
- For triangle $JKL$:
$$\frac{JK}{JL} = \frac{9.45}{19.59} \approx 0.4823$$
Rounded to the nearest hundredth:
$$0.48$$
- For triangle $PQR$:
$$\frac{PQ}{PR} = \frac{75.6}{156.72} \approx 0.4825$$
Rounded to the nearest hundredth:
$$0.48$$
- For triangle $XYZ$:
$$\frac{XY}{XZ} = \frac{85.05}{176.31} \approx 0.4824$$
Rounded to the nearest hundredth:
$$0.48$$
4. **Use calculator to find trigonometric values:**
- $$\sin 61.2^\circ \approx 0.48$$
- $$\cos 61.2^\circ \approx 0.48$$ (calculator value is about 0.4848 but we will confirm below)
- $$\tan 61.2^\circ \approx 1.80$$ (calculator value about 1.80)
Using a calculator:
$$\sin 61.2^\circ \approx 0.88$$
$$\cos 61.2^\circ \approx 0.48$$
$$\tan 61.2^\circ \approx 1.83$$
5. **Compare ratios to trigonometric functions:**
The ratios from part (a) are approximately $0.48$, which matches the cosine value, not sine.
6. **Conclusion:**
- The ratio of the side opposite to the hypotenuse is approximately $0.48$ for all triangles.
- The sine of $61.2^\circ$ is approximately $0.88$.
- The cosine of $61.2^\circ$ is approximately $0.48$.
- The tangent of $61.2^\circ$ is approximately $1.83$.
- Since the ratio matches the cosine value, the ratio in part (a) corresponds to the cosine function, not sine.
**Final answers:**
(a)
$$\frac{JK}{JL} = 0.48$$
$$\frac{PQ}{PR} = 0.48$$
$$\frac{XY}{XZ} = 0.48$$
(b)
$$\sin 61.2^\circ = 0.88$$
$$\cos 61.2^\circ = 0.48$$
$$\tan 61.2^\circ = 1.83$$
(c) The trigonometric function giving the ratio in part (a) is **cosine**.