6) Basic log graphs which should be explained in your book. You have a general equation of the line being
log(y)=mlog(x)+c. You know two points on the graph. So you can deduce the equation in this form, yes?
Then once you have it, solving for
y is straight-forward as you simply exponentiation both sides with base 10.
8) Dunno what method you are taught to solve these types so here is one. The argument of sine
2θ while the range is only for
θ. We want to be for
2θ so we multiply through the range to get
0<2θ≤4π. Then you only need to arcsin both sides to get your principal value of
2θ, call this
P=arcsin(0.7) (also arcsin means sine inverse, in case you don't know). Another value is
π−P. Then any further solutions would be achieved by adding on
2π onto both of these answers.