Question 873498
let wire length be x								
The rope the floor & the pole form a right triangle.								
The base is one leg	The height is the other 

By Pythagoras theorem									
Hypotenuse^2 = Leg1^2+leg2^2									
{{{	x 	^2	=	30	^2	+	40	^2}}}	
x 	^2	=	900	+	1600				
x 	^2	=	2500						
{{{ sqrt(x^2)=		sqrt(	2500	)}}}					
x=	50	m