Hima asked in Science & MathematicsMathematics · 1 month ago

# Trigonometry: Bearings Question?

Feeling like a bad tutor for not being able to fully solve this lol. In Q6 I’ve managed to find the triangle’s angle at the yacht corner, 92. I can’t seem to be able to find another side for the triangle in order to use cosine/sine rule.

For Q7 the two sides given (AB from Q6 and 1.2km is all I have :/

Relevance
• 1 month ago

Q6

Draw a vertical line representing the coast, sea is to the right, land is to the left. A is down, B is up on that line. Point C representing the yacht is in the middle right. Connect the points. Angle in A is 90-32 = 58°. Angle in B is 300-270=30°

Angle in C is 180-58-30=92°.

We also know AB=2.2 km.

Use Law of Sines:

AB/sin C=BC/sin A = AC/sin B

BC= AB sinA / sin C

BC= 2.2 sin 58° / sin 92°= 1.867 km

BC=1.9 km (rounded to 1 d.p.)

AC = AB sin B / sin C

AC = 2.2 sin 30° / sin 92°= 1.101 km

AC = 1.1 km (rounded to 1 d.p.)

Q7.

BC = 1.2km

angle B = 315-270 = 45°

Law of Cosines

AC^2 = AB^2 + BC^2 - 2 AB BC cos B

AC^2 = 2.2^2 + 1.2^2 - 2*2.2*1.2*cos 45°

AC^2 = 2.546

AC= 1.6 (to 1 d.p.)

• 1 month ago

You have one side, 2.2km and one angle of 92°. This is not enough info you two angles or two sides in order to solve this problem