If ABCD is a square and BCE is an equilateral triangle, what is the measure of $\angle DEC$?
The figure shows a circle of diameter AB and radius 6.5 cm. If chord CA is 5 cm long, find the area of $\triangle ABC$.
In $\triangle ABC$, $\angle B$ is a right angle, $AC = 6$ cm, and $D$ is the mid-point of $AC$. The length of $BD$ is