Answer:
D = sqrt[ (2-4)^2 + (7- (-1))^2] = ~8.2
Step-by-step explanation:
D = sqrt[ (Fx-Gx)^2 + (Fy- Gy)^2]
For this case we must simplify the following expression:

We eliminate the parentheses taking into account that:

So, we have:

We add similar terms taking into account that:
Different signs are subtracted and the sign of the major is placed:

Answer:

Hello :
the center of this cercle is : O( 0, 0)
calculate the slope m of the line : OA .. A (3,-4)
m= (yA - yO) / (xA- xO)
m = (-4-0)/(3-0)
m= -4/3
if : k the slope of the tangent : k×m = -1 (the tangent perpendiclar of : OA)
k× (-4/3) = -1
k = 3/4
an equation of this tangent is : y - (-4) = (3/4)(x-3)