12.3.8 Evaluate sec2 ti + 1 + tz j ) dt 12.3.9 Evaluate (8t i + t] - k) dt 0 12.3.10 Evaluate It/2 [(a cost)i + (asint)j + k dt 0 12.3.11 Find r(t) that satisfies the initial condition T' (t) = 4e2ti + 3etj, r(0) = 21 12.3.12 Find r(t) that satisfies the initial condition T' ( t ) = 1 1+t2 it= j +- k, r(1) = 21 t