Given that a measures 25.1 mm, x measures 51.2 mm and angle b measures 82°, find the length of y -

Answer 1

If y is the third side of a triangle, you could use the cosine rule, where
a,b are lengths of adjacent sides, and C is the included angle between a and b.
then the length of the third side, c, is given by:
c²=a²+b²-2ab cos(C)