Given triangle ABC, which equation could be used to find the measure of ∠C? right triangle ABC with AB measuring 6, AC measuring 3, and BC measuring 3 square root of 5 a cos m∠C = 2 square root of 5 all over 5 b cos m∠C = square root of 5 over 5 c tan m∠C = square root of 5 over 2 d tan m∠C = one half