In the triangle ABC, the cosine of ∠ A is 5 / 13, and the cosine of ∠ B is 4 / 5?

In the triangle ABC, the cosine of ∠ A is 5 / 13, and the cosine of ∠ B is 4 / 5?

cosC=cos(π-A-B)=-cos(A+B)
=-cosAcosB+sinAsinB
=-5/13*4/5+√[(1-(5/13)²])√[(1-(4/5)²]
=-4/13+12/13*3/5
=-20/65+36/65
=16/65

Elden Ring Premiere

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