Pythagorus

There is a mast that is 70 m high. A wire goes to the top of the mast at an angle of 68°. How long is the wire?

• Step 1 The two sides we are using are Opposite (70) and Hypotenuse (x).

• Step 2 SOHCAHTOA tells us we must use Sine.

• Step 3 Write down the fraction for sin 68° = 70/w

• Step 4 Solve:

The unknown length is on the bottom (the denominator) of the fraction!
So we need to follow a slightly different approach when solving :

Start with:		sin 68° = 70/w
Multiply both sides by w:		w × (sin 68°) = 70
Divide both sides by "sin 68°":		w = 70 / (sin 68°)
Calculate:		w = 70 / 0.9271... = 75.5 m (to 1 place)

The length of the wire = 75.5 m

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