PLZ GIVE EXPLANATIONS AND ANSWERS ASAP

questions..

The circle C with centre (a,b) and radius 5 touches x-axis at (4,0)

need to find the values of a and b

find cartesian equation for C

A tangent to the circle, drawn from point p(8,17) touches the circle T

find the length of PT to 3sf

2)

the point A has cooridinates 2,5 and point b has coordinates (-2,8)

find in cartesian form and equation of the circle with diamitar AB

PLZ GIVE EXPLANATIONS AND ANSWERS ASAP