Fred is building a model of the bridge shown and he needs to make the triangular support ABC. He has several different pieces of wood at various lengths.
Which of the following three pieces of wood will work for support ABC?
7 in., 9 in., 5 in.
O 6 in., 9 in., 2 in.
O 2 in., 9 in., 7 in.
16 in., 9 in., 7 in.

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?