Let θ be an angle such that tanθ = 15/8 and cscθ > 0. Find the exact values of sinθ and secθ.
a) sinθ = 15/17, secθ = 17/8
b) sinθ = -15/17, secθ = 17/8
c) sinθ = 15/17, secθ = -17/8
d) sinθ = -15/17, secθ = -17/8