Question

In ∆bc , if a =13 ,b =14 , and c = 15 then find the value of cosa

Answer 1

Step-by-step explanation:

GIVEN Here, in triangle ABC, a= 13, b= 14, c=15 & angle A is opposite to side ‘a'

So, 13² = 14² +15² -2 *14*15*Cos A

=> 169 - 421 = - 420 *CosA

=> -252 = -420 * CosA

=> CosA = -252 / -420 = 3/5