Application: In a right triangle, ∠ α (non-right angle), the opposite side of sinα=∠α=∠α/the hypotenuse of ∠α.
sin(α+β)=sinα cosβ+cosα sinβ
sin(α-β)=sinα cosβ-cosα sinβ
sin(2a)=2sina*cosa
Extended data theorem
Sine function theorem: in a triangle, the ratio of sine of each side to its diagonal is equal, that is, a/sin A = b/sin B = c/sin C.
Application of sine function theorem in calculating triangle area
S△=c2sinAsinB/2sin(A+B)(S△ is the area of a triangle, with three angles ∠A∠B∠C and opposite sides respectively).
Sdelta =1/2acsinb =1/2bcsina =1/2absinc (three angles ∠A∠B∠C, opposite sides are A, B and C respectively, see trigonometric function).
In addition, when the value of sin is between 180~360, a negative value will appear, and it will appear repeatedly above 360.
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Remarks: If claw machi