i don't know what theyre getting atQuote:

If both u X v = 0 and u.v = 0, what can you conclude aboutuorv

im not sure where to start here, please helpQuote:

Find velocityv, accelerationa, and speed s at the indicated time t = t1 forr(t) = sin2ti+ cos3tj+ cos4tk; t1 = pi / 2