If cos squareroot 9110 and sin 810 find Solutionacostco

If cos (+) = - squareroot 91/10 and sin (+) = 8/10 find

a)cos(-t)=cost =-91 /10

b)cos(t+ )=-cost=91 /10

c)cos( /2 -t)=sin(t)=3/10

d)cos( /2 -t)=sin(t)=3/10

e)sin(-t)=-sint(t)=3/10

f)sin(t+ )=-sint=-3/10

g)sin(-t)=sint=3/10

h)sin( /2 -t)=cos(t)=91 /10