You need to know the properties of each function.
Tan is opposite (y) over adjacent (x).  Sin>0 means that sin is positive, therefore, it is located on either quadrant 1 or 2. Tan=4/3  so it is located in quadrant 1.
The side of the triangle must be Adjacent=3  opposite=4 and hypotenuse=5
Now, you are asked to find the half angle of Cos which is 

By following the formula, cos=3/5 then:

    Multiply everything (inside the square          

                  root) by 5


                Then just simplify

      The answer is Square root of 20 over 5
 
        
        
        
Answer:
100°
Step-by-step explanation:
360 degrees around a point.
140 + 120 = 260
360 - 260 = 100