The inverse would make the inputs the outputs (switching the x's and y's) because plugging in 4 into the inverse would somehow output 4 and 5, the inverse could not exist. plug in the inverse points to see that the vertical line test would fail.
To find the answer, use 
, and then use the equation 
To find it's half life.
Answer:
42°
Step-by-step explanation:
This is right triangle and sum of 2 angles is 90°:
y+48°=90°
so y= 90°- 48°= 42°
