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Firstly when you read the question you should label the hypotenuse, adjacent and opposite sides on the triangle.

The 3 formulas that you will need in order to find a missing side are:
SOH: Sin = o/h
CAH: Cos = a/h
TOA: Tan = o/a

Right-angles triangle
Find the length of side BC.

image: 7cm traingle (     

You are given the hypotenuse and you can label line AC as adjacent (its next to the angle) and you need to find the opposite line/BC.
Therefore you need to use the Sin (o/h) formula.
So press the sin button on your calculator and type the angle you have been given and press =
Sin(30 and that should equal 0.5
Then you need to  multiply it by the length of the side you've been given.
0.5 x 7 = 3.5 and then line




you say non rightangled triangle but you've put the right angle sign on the 3rd triangle

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