1. **Problem statement:**
- Question 6: In triangle KLM, KM = 6 cm and angle KLM = 30°. Find the length of KL.
- Question 7: In triangle PQR, angle QPR = 45° and PQ = 12 cm. Find the length of PR.
2. **Relevant formula:**
For right triangles, use the trigonometric ratios:
- $$\sin \theta = \frac{\text{opposite}}{\text{hypotenuse}}$$
- $$\cos \theta = \frac{\text{adjacent}}{\text{hypotenuse}}$$
- $$\tan \theta = \frac{\text{opposite}}{\text{adjacent}}$$
3. **Question 6 solution:**
- Given: Right triangle KLM with right angle at L (implied by the problem), KM = 6 cm, angle KLM = 30°.
- We want to find KL.
- In triangle KLM, angle KLM is at vertex L, so KL is adjacent to angle 30°, and KM is the hypotenuse.
- Using cosine:
$$\cos 30^\circ = \frac{KL}{KM}$$
- Substitute known values:
$$\cos 30^\circ = \frac{KL}{6}$$
- Multiply both sides by 6:
$$KL = 6 \times \cos 30^\circ$$
- Recall $$\cos 30^\circ = \frac{\sqrt{3}}{2}$$
- So:
$$KL = 6 \times \frac{\sqrt{3}}{2} = 3\sqrt{3}$$
- Simplify:
$$KL = 3\sqrt{3} \text{ cm}$$
4. **Question 7 solution:**
- Given: Right triangle PQR with right angle at Q, angle QPR = 45°, and PQ = 12 cm.
- We want to find PR.
- Angle QPR is at vertex P, so PQ is adjacent to angle 45°, and PR is the hypotenuse.
- Using cosine:
$$\cos 45^\circ = \frac{PQ}{PR}$$
- Substitute known values:
$$\cos 45^\circ = \frac{12}{PR}$$
- Multiply both sides by PR:
$$PR \times \cos 45^\circ = 12$$
- Divide both sides by $$\cos 45^\circ$$:
$$PR = \frac{12}{\cos 45^\circ}$$
- Recall $$\cos 45^\circ = \frac{\sqrt{2}}{2}$$
- So:
$$PR = \frac{12}{\frac{\sqrt{2}}{2}} = 12 \times \frac{2}{\sqrt{2}} = \frac{24}{\sqrt{2}}$$
- Rationalize denominator:
$$PR = \frac{24}{\sqrt{2}} \times \frac{\sqrt{2}}{\sqrt{2}} = \frac{24\sqrt{2}}{2} = 12\sqrt{2}$$
- So:
$$PR = 12\sqrt{2} \text{ cm}$$
**Final answers:**
- Question 6: KL = $3\sqrt{3}$ cm
- Question 7: PR = $12\sqrt{2}$ cm
Triangle Sides 358B01
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