The angle t is acute and sin t = 6/7 is given use a Pythagorean identity to find cos t

sqrt (1 - 36/49) = + root (13) / 7

Step-by-step explanation:

sin^2t + cos^2t is identical to 1 for all t.

(6/7) ^2 + cos^2t = 1

1 - 36/49 = cos^2t

hence plus/miuns sqrt (1 - 36/49) = cos (t)

since t is acute, the answer must be positive.