Pythagorean Theorem- I'm stumped, please help

Find the value of tan theta if sin theta = 12/13 and theta is in quadrant 2

David estimated he had about 20 fish in his pond. a year later, there were about 1.5 times as many fish. the year after that, the number of fish increased by a factor of 1.5 again. the number of fish is modeled by f(x)=20(1.5)^x. create a question you could ask that could be answered only by graphing or using a logarithm.

Determine the equivalent system for the given system of equations: 5x − 3y = 6 x + y = 2