Based on your question where as to sketch the solid that is described be the given inequalties(cylindrical coordinates) and and i could only give you this answer
r≤zand
r=x2+y2−−−−−−√so we have
x2+y2−−−−−−√=z⟹x2+y2=z2which, if you know it, is the equation of a cone
notice you can sort of see the pythagorean theorem hidden in it
