Answer
part 1 = c/a
part 2 = b/a
Sine is the ratio of opposite to hypotenuse respect to as agiven angle while tangent is the ratio of opposite to adjacent lengths of agiven angle.
Part 1
Sine = opposite/hypotenuse
SinB = b/a
Tangent = opposite/adjacent
TanC = c/b
SinB × TanC = b/a×c/b
= c/a
Part 2
SinC = c/a
TanB = b/c
SinC×TanB= c/a×b/c
=b/a