# Thread: Find the vlue of 4(cos A + cos B + cos C) if...?

1. ## Find the vlue of 4(cos A + cos B + cos C) if...?

In a triangle ABC, if 3R = 4r, value of 4(cos A + cos B + cos C) is? (R and r in the triangle have usual notations)

Ans: 7

How? I couldn't get 7.

2. Originally Posted by fardeen_gen
In a triangle ABC, if 3R = 4r, value of 4(cos A + cos B + cos C) is? (R and r in the triangle have usual notations)

Ans: 7

How? I couldn't get 7.
Please explain what R and r are... Because your usual notations are not necessarily everybody's usual notations...

3. Hello, moo!

Traditionally, these are the accepted definitions . . .

. . $R$ is the circumradius, the radius of the circumscribing circle.

. . $r$ is the inradius, the radius of the inscribed circle.