Answer:
sin(t) = 4*sqrt(5) / 21; cos(-t) = 19/21
Explanation:
think of a right triangle with an adjacent leg a, opposite leg b, and hypotenuse c.
cos(t) = a/c = 19/21. so we can assume a=19 and c=21.
using Pythagorean's theorem, find b: b = sqrt(21^2 - 19^2) = 4*sqrt(5) or 8.944
since tan(t)> 0, b/a > 0 and a is positive so b must be positive. using this information, we know sin(t) = b/c = 8.944/21 or 4* sqrt(5) / 21
since cos x is an even function, cos(-x) = cos x so cos(-t) = cos(t) = 19/21