Question

9. In any triangle ABC, prove that cos A + cosB + cos C NIC

JEE/Engineering Exams

Maths

Solution

102

4.0 (1 ratings)

since ( C=pi-A-B ), we want to maximize the function: ( f(A, B)=cos (A)+cos (B)+cos (pi-A-B) ) ( f(A, B)=cos (A)+cos (B)-cos (A+B) ) within the region R: ( A+B