Can someone help me with these

Si la base de un triángulo isósceles mide 70 m y el ángulo opuesto a ésta mide 58°; entonces ¿cuánto mide la altura de dicho triángulo? a) 21.87 m. b) 40.01 m. c) 43.74 m. d) 63.14 m.

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.

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?