Which expression is equivalent to Cosine (StartFraction pi Over 12 EndFraction) cosine (StartFraction 5 pi Over 12 EndFraction)
2 answers:
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If you take a look at my really poorly drawn diagram, we can see it is a trigonometry problem. The angle, however, is outside the triangle, and we can find the angle inside the triangle next to it by taking it away from 90°:
90°0' - 72°54' = 17°6' ≈ 17.1°.
We can find the other angles becuase one is 90° and the other is:
180°-90°-17°6'=72°54' ≈ 72.9°(which you can see if you know your angle theorems).
We now have diagram 2, nicely simplified so we can see where to go.
Using the Sine Rule, i.e.
We can rearrange to find our length b:
Substituting numbers in:
b=366 feet.
90°0' - 72°54' = 17°6' ≈ 17.1°.
We can find the other angles becuase one is 90° and the other is:
180°-90°-17°6'=72°54' ≈ 72.9°(which you can see if you know your angle theorems).
We now have diagram 2, nicely simplified so we can see where to go.
Using the Sine Rule, i.e.
We can rearrange to find our length b:
Substituting numbers in:
b=366 feet.