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
In trigonometry, we start from the point (1,0), so this is the 0-degree point. Then, we start rotating counter clockwise along the unit circle.
Note that rotating 180 or -180 degrees is actually the same, because you travel half the circumference clockwise or counter clockwise. In both cases, you start from the rightmost point of the circle, (1,0), and arrive at the leftmost point, (-1,0).
Now, for every point (x,y) on the unit circle, given by a certain angle
, we have

So, in this case, the angle of -180 is associated with the point (-1,0), and thus we have

U should get the app "photomath" it will help u out alot!!!
Sin = Opposite/ Hypotenuse
Sin (theta)= 5/10
Sin^-1(5/10)=30
theta=30