1. **Problem statement:** We have a triangle PQR with sides PQ = 5 m, QR = 13 m, and angle PÔQ = 90°. Q is on a bearing of 126° from P.
2. **(a)(i) Find the bearing of P from Q:**
- Bearing from P to Q is 126°.
- Bearing from Q to P is the opposite direction, so add 180°:
$$126^\circ + 180^\circ = 306^\circ$$
3. **(a)(ii) Find the bearing of P from R:**
- Given bearing from P to Q is 126°.
- The bearing of P from R is calculated as:
$$180^\circ - 126^\circ = 54^\circ$$
4. **(b)(i) Work out length PR:**
- Using the cosine rule in triangle PQR:
$$PR^2 = PQ^2 + QR^2 - 2 \times PQ \times QR \times \cos(\angle PÔQ)$$
- Since $\angle PÔQ = 90^\circ$, $\cos 90^\circ = 0$, so:
$$PR^2 = 5^2 + 13^2 = 25 + 169 = 194$$
- Therefore:
$$PR = \sqrt{194} \approx 13.928$$
5. **(b)(ii) Write down the value of $\cos PÔR$ as a fraction:**
- The angle $PÔR$ corresponds to the difference in bearings between P and R from O.
- Given bearings 306° and 360°, the fraction is:
$$\frac{306}{360} = \frac{17}{20}$$
**Final answers:**
- (a)(i) Bearing of P from Q = $306^\circ$
- (a)(ii) Bearing of P from R = $54^\circ$
- (b)(i) Length PR $\approx 13.928$ m
- (b)(ii) $\cos PÔR = \frac{17}{20}$
Triangle Bearings 2E09F0
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