A scalene triangle has side lengths a=xcm, b=10cm and c=15cm. The angle A=105 degrees is opposite side a. Using the cosine rule, find the value of x to 3 s.f.
The cosine rule= a2 = b2+c2-2bcCos(A)a2= 102+152-(2x10x15xCos(105))a2= 402.65...Square root of ans.a= 20.07x=20.1cm
