while loop not initializing

Hello all. Basically, I'm new to C programming but not necessarily to programming. I'm a college student and took a semester of Java, so I understand many of the fundamentals. However, I'm having issues with the while loop in my code not initializing if the condition is met.

#include <stdio.h>

#define PI 3.141593f

int main(void)
{
  float length = 0.0;
  float radius = 0.0;
  float check = 0.0;
  
  printf("ACME Truck Company\n");
  printf("This program will calculate the volume and surface area of the x-11 cylindrical tank.");
  
  printf("\nEnter the length of the tank (feet): ");
    scanf("%f", &length);
  printf("Enter the radius of the tank (feet): ");
    scanf("%f", &radius);
    
  while(length <= 10.0 && length >= 20.0) {
    printf("User input is invalid, please enter a value between 10 and 20: ");
      scanf("%f", &length);
      
    check = (length / 2);
    
    if(check <= radius) {
      printf("User input is invalid, please enter a value between %f and 20: ", length);
	scanf("%f", &length);
    }
  }
}

Obviously, there is more to the program, but this needs to be solved before I can move on. Some context: The idea of the program is to calculate the volume and surface area of a cylindrical tank with concave spheres on the ends. However, the length can only be between 10 and 20, and the radius between 3 and 6. Also, should the radius be more than half the length of the container, the tank would not be possible because the concave spheres would overlap.

I thank anyone in advance who can offer help. Thanks!