What is the exact area of triangle with measures a=6 b=7 and cos C = 1/4

The area of the triangle is A = (1/2) absinγ

(sinγ) Λ2 + (cosγ) Λ2=1 = > sinγ=√1 - (cosγ) ∧2 = √1 - (1/4) ∧2=√1 - (1/16) = √ (15/16) = √15/4

A = (1/2) * 6*7*√15/4=21*√15/4 = (21/4) √15

Good luck!