Write 2 sides that are proportional as a fraction.

take the logarithm of both sides (the base of the log doesn't matter):

apply the exponent property - this says that :

distribute the log terms on both sides:

group like terms together:

divide through both sides by the coefficient on :

you can do some additional rewriting here using the properties of the logarithm to simplify things if you like:

d. you cannot tell because there are no values shown.

dont't really have enough info here but its likely

sss for the three sides being congruent ( its stands for side side side)

or

sas   for side angle side.   so a side is congruent and and angle and a side