The first set of equations is
x = t^2 and y = t + 1
Re-arranging the second one, we have y - 1 = t and substituting this one into the first one, we have :
x = (y - 1)^2 which is a "sideways" parabola opening to the right with a vertex at (0, 1)
a) x = sin^2t y = sint + 1
Rearranging the second one again, we have sint = y - 1 and substituting this one into the first we have
x = (y - 1)^2
However......this graph is a "restricted" version of the first one......from t = 0 to t = pi/2, the graph traces the same path from the vertex (0,1) to the point (1, 2).....then from t = pi/2 to t =pi.....it "reverses" course from (1,2) back to the vertex......from t = pi to t = 3pi/2, it traces the same path as the original graph from the vertex to the point (1, 0)...lastly, from t = 3pi/2 to 2pi......the graph again reverses course and ends back at the vertex.......this behavior is repeated infinitly
Here's the graph :

b) x= t^4 y = t^2 + 1
Rearranging the second equation, we have y - 1 = t^2
Substituting this into the first equation we have the original equation, again, x = (y - 1)^2
However, this graph is just the [unbounded] upper half of the parabola since y is never less than 1
For the interval where t ranges from (-infinity, 0), the graph traces back from the right to the point (0, 1).....when t ranges from (0, infinity), the gragh "reverses" course and traces back to the right
Here's the graph here traced from t = -2 to t = 2 :

