It is radius! Hope this helps!! :)
1/3 of the wall is covered in stone
h = 50 cos ( pie(x - 10 )/15 ) + 52
80 = 50 cos ( pie( x - 10 )/15 ) + 52
80 - 52 = 50 cos ( pie( x - 10 )/15 )
28 = 50 cos ( pie( x - 10 )/15 )
cos ( pie( x - 10 )/15 ) = 28/50
cos ( pie( x - 10 )/15 ) = 56/100
cos ( pie( x - 10 )/15 ) = cos ( 56 )
cos ( pie( x - 10 )/15 ) = cos ( 0.3111 pie )
Thus ;
pie( x - 10 )/15 = 0.3111 pie
( x - 10 )/15 = 0.3111
x - 10 = 15 × 0.3111
x - 10 = 4.6665
x = 10 + 4.6665
x = 14.6665 [ approximately ]
Thus the correct answer is exactly what u chose goodjob .....
