^2 means squared.
tan ^-1 means tangent inverse.

For (a), use Pythagorus' Theorem for the side of the triangle.

For (b), remember tangent inverse (opposite / adjacent) to find angle?

For (c), make use of the angle you found in (b), then use sin, since you already have the hypotenuse and you are finding the opposite.

For (d), see the total area as 3 different figures, it will help to simplify things a lot.

Hope this helps. :)