Two sides of a triangle have lengths 9 m and 10 m. The angle between them is increasing at a rate of 0.06 rad/s. Find the rate at which the area of the triangle is increasing when the angle between the sides of fixed length is 60°.$\displaystyle A=\frac{1}{2}bh$

$\displaystyle \frac{dA}{dt}=\frac{1}{2}[h\frac{db}{dt} +b \frac{dh}{dt}]$

$\displaystyle \frac{dx}{dt}= .06$

How do I relate relate area to the angle?