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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

Answered by Laurie R. • Maths tutor

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