Part B โ Trigonometry
B1.โ
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From a point $A$ the angle of elevation to the top of a vertical tower is $30ยฐ$. From $B$, which is $40$ m closer along the same straight line, it is $50ยฐ$. Find the height of the tower (2 d.p.).
(Hint: let height $=h$, distance from $B$ to the foot $=d$; use $\tan50=\tfrac{h}{d}$ and $\tan30=\tfrac{h}{d+40}$.) Height $=$
B2.โ
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A ship sails $12$ km from $P$ on a bearing of $050ยฐ$T, then $16$ km on a bearing of $140ยฐ$T to reach $Q$.
(a) Show the two legs are at right angles.
(b) Find $PQ$.
(c) Find the bearing of $Q$ from $P$ (nearest degree).
(b) $PQ=$ (c) bearing $=$
B3.โ
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A right pyramid has a square base of side $10$ cm and apex $12$ cm above the centre.
(a) Find a slant edge (apex to base corner), exact & to 2 d.p.
(b) Find the angle a slant edge makes with the base (1 d.p.).
(Hint: centre-to-corner $=$ half the base diagonal.)
(a) slant $=$ (b) angle $=$
B4.โ
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A drone hovers $80$ m above a straight road. The angle of depression to a car is $25ยฐ$, and to a person beyond the car is $15ยฐ$. Find the distance between the car and the person (2 d.p.). Answer:
B5.โ
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An equilateral triangle has side length $2\sqrt3$ cm. Find its
exact area (surd form). Area $=$