Final answer:
The equation for the plane y=5 in cylindrical coordinates is r=5sin(θ).
Step-by-step explanation:
The equation for the plane y=5 in cylindrical coordinates can be expressed as r=5sin(θ). In cylindrical coordinates, 'r' represents the distance from the origin to the point, and θ represents the angle from the positive x-axis to the point. So, a value of r=5sin(θ) would give us all the points on a circle with radius 5, centered at the origin, that lie in the plane y=5. The sin(θ) component ensures that the points lie in the upper half of the circle (y>0).