In each of 8 through 12 proceed as in 7. (a) Transform the given system into a single equation of second order. (b) Find x1 and x2 that also satisfy the given initial conditions. (c) Sketch the graph of the solution in the x1x2-plane for t 0.

L3 - 2 3. Two basic triangles π/3 π/6 π/4 4. Unit circle (r =1 ,osi θ = y and cosθ = x) π/2 2π/3 π/3 3π/4 π/4 π/6 5π/6 π 0 7π/6 11π/6 5π/4 7π/4 4π/3 5π/3 3π/2 θ 0