# sine and cosine rule

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#1
i know this is basic stuff but i can never remember when to use sine or cosine rule? help! does anyone know any easy ways of remembering it, anything?! would be greaaattt!!!
0
8 years ago
#2
if you two side either side of an angle and you want to find the third or have three sides and want to find an angle - use cosine
otherwise sine will work
0
8 years ago
#3
You might have already came accross it but SOH CAH TOA

So SOH = Sin(angle) = Opposite / Hypotenuse
CAH = Cosine(angle) = Adjacent / Hypotenuse
TOA = Tangent(angle) = Opposite / Adjacent

If you don't get why it's supposed to be easy to remember try saying it :P It sounds funny. When I say opposite I mean the side opposite to the angle You'll notice they are all in order too as to when they appear in the equation.

Hope this helps
0
8 years ago
#4
(Original post by k4l397)
You might have already came accross it but SOH CAH TOA

So SOH = Sin(angle) = Opposite / Hypotenuse
CAH = Cosine(angle) = Adjacent / Hypotenuse
TOA = Tangent(angle) = Opposite / Adjacent

If you don't get why it's supposed to be easy to remember try saying it :P It sounds funny. When I say opposite I mean the side opposite to the angle You'll notice they are all in order too as to when they appear in the equation.

Hope this helps
You may not have done the Sine and Cosine Rule yet, so perhaps you did not understand why the OP was asking
0
8 years ago
#5
(Original post by TenOfThem)
You may not have done the Sine and Cosine Rule yet, so perhaps you did not understand why the OP was asking
Ahh I did think it was a bit of an obvious question :P I'm guessing it's C2 or C3??
0
8 years ago
#6
(Original post by mmollyyyyyy)
i know this is basic stuff but i can never remember when to use sine or cosine rule? help! does anyone know any easy ways of remembering it, anything?! would be greaaattt!!!
Make sure that you label the triangle correctly
Vertices are capitals and sides are lowercase

You will be given 3 pieces of information and asked to find a 4th
the information given will only fit one of the rules

The Sine Rule requires 2 angles whereas the Cosine Rule only needs 1
0
8 years ago
#7
(Original post by k4l397)
Ahh I did think it was a bit of an obvious question :P I'm guessing it's C2 or C3??
GCSE
0
8 years ago
#8
(Original post by TenOfThem)
GCSE
*facepalm* just realised what it was xD I had a moment ignore me :P
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