In , which of the following is…

MATHEMATICS · Single correct · ISC · Mathematics · Sets and Functions · Sets and Functions

Problem

In △ABC\triangle ABC, which of the following is true? (1) (b+c)cos⁡A2=asin⁡(B+C2)(b+c)\cos\frac{A}{2}=a\sin\left(\frac{B+C}{2}\right) (2) (b+c)cos⁡(B+C2)=asin⁡A2(b+c)\cos\left(\frac{B+C}{2}\right)=a\sin\frac{A}{2} (3) (b−c)cos⁡(B−C2)=acos⁡A2(b-c)\cos\left(\frac{B-C}{2}\right)=a\cos\frac{A}{2} (4) (b−c)cos⁡A2=asin⁡(B−C2)(b-c)\cos\frac{A}{2}=a\sin\left(\frac{B-C}{2}\right)

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