Question

cos31=2.1/x

Answer 1

does this say
\[\cos(31)=\frac{2.1}{x}\]? if so you solve for x via
\[x=\frac{2.1}{\cos(31)}\]

Answer 2

i get 2.45 rounded, assuming you are working in degrees

Answer 3

what is the asnwer to tanx=5

Answer 4

78.69