In any ΔABC, prove that

1

In any ΔABC, prove that

a(b cos C – c cos B) = (b² – c²)

2

In any ΔABC, prove that

ac cos B – bc cos A = (a² – b²)

4

In any ΔABC, prove that

5

In any ΔABC, prove that

2(bc cos A + ca cos B + ab cos C) = (a² + b² + c²)