If the terminal edge of an angle passes through point P (1, √ 3), what is the tan value of the angle

If the terminal edge of an angle passes through point P (1, √ 3), what is the tan value of the angle

The tan value of this angle = Y / x = radical 3 / 1 = radical 3

Given that the point P (Tan α, cos α) is in the third quadrant, which quadrant is the terminal edge of angle α
There is another problem: 0 < α < π / 2, if sin α - cos α = radical 5 / 5, find the value of 2Sin α × cos α - cos α - 1 / 1-tan α

1、
The third quadrant is tan α

How can four five be equal to 0.8
And addition, subtraction, multiplication and division can be used at most once

(5-5÷5)÷5=0.8