physics
posted by projectile motion .
A boy sitting on the edge of a vertical cliff fires a rock with a slingshot at a velocity of 16.45758956 m/s and an angle of 59.78 degrees above the horizontal.
The rock lands in a lake at the base of the cliff, a horizontal distance of 89.67 meters beyond the base of the cliff. How high is the cliff in meters?
i got an answer of y=420.2599461m
is this right??

No. How could a height be negative?
Did you make up this problem? I makes not sense using ten significant figures.
Show your work if you want your error to be found. 
The height of cliff is 560.4946206m