If x = a (cos t + t sin t) and y = a (sin t – t cos t), then find the value of at

43

If , then find the value of .

44

If x = a sin t and , find .

46

If , y = a sin t, evaluate at

47

If x = a (cos 2t + 2t sin 2t) and y = a (sin 2t – 2t cos 2t), then find .