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Grade 11Trigonometry

In 🔺 ABC, 2ca.sin(A-B+C)/2 is equal to... (a) a²+b²-c² (b) c²+a²-b²(c) b²-c²-a² (D) c²-a²-b²

Profile image of Suraj Prajapati
8 Years agoGrade 11
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1 Answer

Profile image of Arun
8 Years ago
A+B+C=Pi

so A+C = Pi - B

so here it will be :  2ac.sin(Pi/2 -B) = 2ac.cosB

by cosine rule, we have: c2+a2-b2 = 2ac cos B

option B

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