This self checking worksheet asks the students to find the area of an oblique triangle given two sides and the included angle. But, sometimes, the triangles will have the wrong two angles. Then the students will need to find the third angle by subtracting from 180, then find the area of the triangle. But, also, they will be given the correct angle, but one extra angle to see if they know what they are doing. When finished, the student will find the solution to a riddle.