In ΔABC, what is the value of cos B? A.5/13 B. 12/13 C. 5/12 D. 13/12

Can someone tell me if this is perpendicular? !

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?

You went to a restaurant and spent $53.25 on the meal. there was a 6% sales tax. what was the amount of money, not including a tip, you spent at the restaurant?