Question

plz tell this answer

Answer 1

Start with the formulas for volume and slant area in terms of h and r: 

V = (π/3) r² h ... volume of a cone 
C = π r √(h² + r²) ... lateral area of a cone 

Looking again, that "22/7" in your first term looks suspiciously like an approximation to π. If it is, the statement is false. It is at best an "approximately equal" statement. Test: 

3π V h^3 = 
C² h² = π² r² (h² + r²) h² 
9V² = π² r^4 h² 

So, combine those: 

3πVh^3 - C²h² + 9V² = (π² r² h^4) - [π² r² (h² + r²) h²] + (π² r^4 h²) 
= π² r² h² [ h² - (h² + r²) + r²] ... factoring out π², r² and h² from each term 

But the [] bracketed sum is h² - h² - r² + r² = 0, for any values of h and r, so the product is also zero, and that' proves that: 

3πVh^3 - C²h² + 9V² = π² r² h² (0) = 0