### What's the sine rule?

a/Sin A = b/Sin B = c/Sin C

Sin A/a = Sin B/b = Sin C/c

Where side a is opposite angle A, side b is opposite angle B, side c is opposite angle C.

What do we use it for?

The Sine Rule is a more advanced formula that be used to find missing sides and angles in any triangle, whether it has a right angle or not.

### When can we use it?

You will be given a side and its opposite angle.
If you are a given another side, you can calculate its opposite angle using the Sine Rule.
If you are given another angle, you can calculate its opposite side using the Sine Rule.

For example

[picture missing]

We know:

a = 4cm
A = 40o
b = 3cm

What is B?

4/40 = 3/B

Rearrange this to get

B = 3 x 40/4 = 30

Nothing in this section yet. Why not help us get started?

## Related Topics

Requires a knowledge of…

After this move on to…

## Related Questions

• 1
Vote
4

### What is a coordinate grid?

By Ryan McGuire on the 10th of January, 2013

• 1
Vote
3

### What is the general form for a quadratic equation?

By Filsan on the 10th of January, 2013

• 1
Vote
2

### What does the graph of Y = x Linear look like?

By Filsan on the 10th of January, 2013

• 1
Vote
3

### What is the equation of a straight line graph?

By Filsan on the 10th of January, 2013

• 0
4

### How do I find 15% of a value?

By Verity Painter on the 8th of January, 2013

• 1
Vote
2

### What is an index law?

By Filsan on the 6th of December, 2012

• 0
1

### What does write the terms of a sequence mean?

By Filsan on the 6th of December, 2012

• 0
1