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**jamessmith** ( a ) Aa telephone wire hangs between two poles at x = - b and x = b. It takes the shape of a catenary with equation y = c + 7a cosh ( x / 7a ). Find the length of the wire.

( b ) Suppose two telephone poles are 50 ft apart Mr F says: Taking the turning to be at x = 0 this lets you calculate the value of b.

and the length of the wire between the poles is 51 ft.

If the lowest point of the wire must be 22 ft above the ground, Mr F says: Therefore the y-coordinate of the turning point is y = 22.

how high up on each pole should the wire be attached? Round your answer to two decimal places.

I dunno how to do this.