is there a formula for working out the angles of a triangle to make the sides meet at the top?

Question

I am doing a GCSE maths foundation paper for revision and one question has a triangle with the base side being 9cm and the other 2 sides 7.5cm. Is there a formula for finding the angles of the triangle given the lengths of each side so that the 2 side lengths join together at the top to complete the triangle?

Thanks

cosine rule of triangles.this will helpful – iostream007 Jun 09 '13 at 14:44 — iostream007, Jun 09 '13 at 14:44

score 2 · Accepted Answer · answered Jun 09 '13 at 14:43

2

HINT:

Use cosine formula of triangles

$$\cos A=\frac{7.5^2+7.5^2-9^2}{2\cdot7.5\cdot 7.5}$$

answered Jun 09 '13 at 14:43

lab bhattacharjee

274,582

Hi could you explain what's happening here and how I get the angles to form the triangle? – crmepham Jun 09 '13 at 14:49
@crm, follow the link and you'll get a picture. – vadim123 Jun 09 '13 at 14:59

is there a formula for working out the angles of a triangle to make the sides meet at the top?

1 Answers1