Maximizing Triangle Area with Given Adjacent Sides

[Saterial]

Homework Statement

A triangle has adjacent sides 4 cm and 6 cm. Find the angle contained by the sides which maximizes the area.

Homework Equations

The Attempt at a Solution

I'm not going to lie. I have no idea how to start this. I tried using sine law to create a helper equation but that gave me Four unknowns.

 

[dacruick]

You need an equation that relates area of the triangle to the angle.