For the first problem, remember that sin^2 θ + cos^2 θ = 1.

First distribute, and then put every term over sinθcosθ. Group the terms in such a way that you can create sin^2 θ + cos^2 θ by factoring. You will end up with (sinθ+cosθ) / sinθcosθ.

For the second problem, recognize that sinθ = 3/5 is giving you two out of the three sides of a triangle, and with pythagorean theorem you can easily find the third side. Pi/2 < θ < pi gives you the quadrant. From there, just plug in.