Calculate the area of triangle 
with sides 
and 
and angle 
.
Calculate the side length and area of a dodecagon inscribed in a circle of radius 2.
The line PR is the diameter of a circle, and a point T lie on the circumference bounding this circle. As 
measures 
, and the length of the line RT is 
. Calculate the radius and area of this circle.
Take 
.
