The diagram shows a cube of side length 3 inches. The points P, Q, and Rhave the relative locations shown. Pis one of the vertices on the bottom of the cube, Q is located on an edge and is 1 inch from the top of the cube, and R is located
on an edge and is 1 inch from the bottom of the cube.
1 in
Q
P
R
1 in
3 in
If a plane including the points P, Q, and R cuts through the cube, what is the shape of the resulting cross section?

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?