Peyton is walking her dog, Willow, on a local trail and the dog falls 153 feet down a ravine! Payton is overcome with emotion an
d needs your help to save her dog. You can repel down and successfully rescue Willow, but you must calculate how much rope is needed.
The ravine is 153 feet deep the repel line will be the diagonal distance from the top of the ravine to Willow The anchor and repel line form a 35 degree angle; this is angle A in the image below.
(a) Calculate the length of the repel line using one of the 3 trigonometry ratios taught (sin, cos, tan) Round your answer to the nearest whole number. Show all needed math for calculating this length.
The ravine is 153 feet deep the repel line will be the diagonal distance from the top of the ravine to Willow The anchor and repel line form a 35 degree angle; this is angle A in the image below.
(a) Calculate the length of the repel line using one of the 3 trigonometry ratios taught (sin, cos, tan) Round your answer to the nearest whole number. Show all needed math for calculating this length.
1 answer:
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Answer:
(i) see first attached diagram
(ii) QR = 22.67 km (2 dp)
(iii) 243°
Step-by-step explanation:
A bearing is the angle in degrees measured clockwise from north.
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<u>Part (i)</u>
see first attached diagram
<u>Part (ii)</u>
The angles marked in blue on the second attached diagram are Consecutive Interior Angles. In this case they add to 180° as the North lines are parallel.
The sum of angles around a point is 360°
⇒ m∠QPR (shown in red on the second attached diagram) = 360 - 150 - (180 - 15) = 45°
To calculate the distance between Q and R (marked in red on the attached diagram), use the cosine rule.
⇒ QR² = PR² + QP² - 2(PR)(QP)cos(QPR)
⇒ QR² = 32² + 24² - 2(32)(24)cos(45)
⇒ QR² = 513.8839841...
⇒ QR = √513.8839841...
⇒ QR = 22.67 km (2 dp)
<u>Part (iii)</u>
We need to find the angle marked in green on the third attached diagram.
To do this, we need to find the angle marked in pink and the angle marked in orange, then subtract them from 360°
Pink angle = 180 - 150 = 30° (using the same consecutive angle theorem as before)
Orange angle (o) using the sine rule:
⇒ sin(o)/32 = sin(45)/QR
⇒ sin(o) = 32sin(45)/22.67
⇒ sin(o) = 0.9981652337...
⇒ o = 86.52868176...°
Therefore, the green angle = 360 - 30 - 86.52868176... = 243° (nearest degree)
