How do I know when to use SOHCAHTOA and when to use the sine or cosine rule?
First, check whether the triangle in the question is a right angle. If it is then SOHCAHTOA is used every time.
If not, count how many sides we know the length of and how many angles we know the value of. Then check whether we need to calcualte a length or an angle.
The sine rule is then used in the following cases: 2 angles known + 1 length known + 1 unknown length or 2 lengths known + 1 angle known + 1 unknown angle
The cosine rule is used in the following cases: 3 lengths known + 1 unknown angle or 2 lengths known + 1 angle known + 1 unknown length
AR
Related Maths GCSE answers
All answers ▸Factorise fully 3*a^3*b +12*a^2*b^2 + 9*a^5*b^3
Work out 2 and 3/4 x 1 and 5/7 Give your answer as a mixed number in its simplest form.
A square, with sides of length x cm, is inside a circle. Each vertex of the square is on the circumference of the circle. The area of the circle is 49 cm^2. Work out the value of x. Give your answer correct to 3 significant figures.
A straight line L1 has equation y = 2x + 4. L2 is parallel to L1 and passes through the point (3,13). What is the equation of L2?