<span>let landmark be at L ZN = 100, NL = x (say) tan 54 = (100+x)/H 100 + x = H tan 54 -------------- (1) ------------------------------ tan 61 = H/x ................ [alternate angle] x = H cot 61 ------------------------- (2) put x from (2) into (1) H cot 61 + 100 = H tan 54 H = 100 / [tan 54 -cot 61] H = 100 / [1.376 - 0.554] H = 121.65 feet</span><span> </span>