The center of a circle lies on the line y = 3x + 1 and is tangent to the x-axis at (−2,0) .

what is the equation of the circle in standard form?

you don't have to give me the answer, but at least me understand what it is that i need to be looking for in order to solve this problem (step-by-step if it's possible), i'm stuck.

Aspacecraft can attain a stable orbit 300 kilometers above earth if it reaches a velocity of 7.7 kilometers per second. the formula for a rocket's maximum velocity v in kilometers per second is vequalsminus0.0098tplusc ln upper r, where t is the firing time in seconds, c is the velocity of the exhaust in kilometers per second, and r is the ratio of the mass of the rocket filled with fuel to the mass of the rocket without fuel. find the velocity of a spacecraft whose booster rocket has a mass ratio of 20, an exhaust velocity of 2.1 km/s, and a firing time of 15 s. can the spacecraft achieve a stable orbit 300 km above earth?