How do I know which out of the Sine and Cosine rule I should use?

If you look at the formulae for the Sine and Cosine rules you'll see that the Sine rule involves two angles and two sides and the Cosine rule involves one angle and three sides.So have a look at the problem you're given and see how many angles and sides you are given and which ones you're trying to work out:-if you're given: a) two sides and an angle (you're trying to work out the second angle) or b) two angles and a side (you're trying to work out a second side) then use the Sine rule.-if you're given: a) three sides (you're trying to work out an angle) or b) two sides and an angle (yo're trying to work out the third side) then it's the Cosine rule.

JH
Answered by Julian H. Maths tutor

5131 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Expand completely: (3a-6)(a+3)


Divide £700 in the ratio 5:3:2


The number of uniform spherical balls that can be produced from a given mass of lead is inversely proportional to the radius of the ball cubed. If 2744 balls can be made when the radius is 1mm, how many balls can be made when the radius is 1.4mm ?


Factorise x^2+3x+4 without the use of quadratic formula


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning