check my answer

This one is a little difficult

Call Pierre's height above the ground, H

Call the  distance from the base of the bldg to the sports car, D

So...we have this relationship

tan 21°  = H / D    ⇒     D tan 21°  =  H     (1)

Next.....call the distance from the  base of the bldg to the  dump truck = D + 600

So  we have this

tan 14°  =   H  / (D + 600)       sub (1)  in for H

tan14°   =  ( D tan21° )  / (D + 600)       rearrange as

D tan 14° + 600 tan 14°  = D tan 21°

600 tan 14°  =   D ( tan 21° - tan 14°)

[ 600 tan 14° ]  / [ tan 21° - tan 14°]  =  D  = 1112 ft

Sub this back into (1)  to find H  = 1112 tan 21° ≈  426.86 ft

GOOD JOB, JENNY   !!!!!