How are you guys? My teacher signed me an assigment over the summer and im stuck.

the following three questions is

The Angle a, measured in radians, is pi <_ alfa <_ 3/2pi

Calculate Sin alfa, if you know that cos=-14/15

The traingle ABC is 90 degrees, perpendicular at the corner C and alfa degree at the corner. Count a= |BC|, if you know that c = |AB| = 4 and that tan alfa = 1/3

In the triangle ABC is a=|BC|, b=|CA|, c=|AB| and A= alfa, B= beta and C=gamma

find c, the traingle has a obtuse angle at C and a=1, b=3 and sin gamma = 4/7

Pic related