This formula is used for solving triangles which are not right angled and in which either two angles and any side are given or two sides and the angle opposite one of them are given.
Sine Rule:
Example 1:
Find the remaining angles of ABC in which a= 12.5cm, C= 17.7cm and C= 1160
Cosine Rule
The Cosine rule, just like sine rule is used to solve for the unknowns in a triangle. Cosine rule is especially use to solve triangles with the following dimension.
Solution
By Cosine Rule
X2 = a2 + b2 – 2ab Cos 80
X2 = 32 + 22 -2(3)(2) x 0.1736
X2 = 13 – 2.0832
X2 = 10.9168
X2 =
=3.305cm
Join Discussion Forum and do your assignment:
Find questions at the end of each lesson, Click here to discuss your answers in the forum
For advert placement/partnership, write ask@stoplearn.com
Download our free Android Mobile application:
Save your data when you use our free app. Click picture to download. No subscription. 