# Results and Formulas of Plane Triangles

Consider the triangle$\Delta ABC$, having the angles $\alpha ,\beta ,\gamma$ and sides $a,b,c$ as shown in the figure.

1) Law of Sine is

2) Laws of Cosine are

or

or

or

3) Laws of Tangent are

HALF ANGLE FORMULAS

Consider that $a,b,c$ and $A,B,C$ are sides and angles of $\Delta ABC$, as shown above, also if (i)

(ii)

4)

5)

6)

7)

8)

9)

10)

11)

12)