We can form a right triangle where the distance between the ranger's current position and fire is the hypotenuse of the triangle. In a right triangle, the tangent of an angle is equal to its opposite side divided by the hypotenuse.
Therefore, we have:
, where is the distance between the base of the tower and the fire.
if the slope of the first problem is -2/7 then its perpendicular is 7/2 (the exact opposite) and since the y- intercept is the b in Y= mx +b the intercept of the equation you’re trying to find is -2