Question

a kite is flown from the top of a building 100m high with a string 41m long. a boy standing 9m away from the building observes the kite just overhead. find the height from the ground at which the kite is flying

Answer 1

LET
AC --- Building
B. --- Boy's position
K. ---- Kite's position
CK. -- String.

In ∆CKM,

By pythagorus theorem,
CK² = KM²+CM²
KM² = CK²-CM²
KM² = (41)²-(9)²
KM² = 1681-81
KM²= 1600
KM= √(1600)
KM=40

Height of ground where kite is flying = KM+MB

So required answer is
$\textbf {40+100=140 m}$

Answer 2

Let:

AC --- Building

B. --- Boy's position

K. ---- Kite's position

CK. -- String.

In ∆CKM,

According to Pythagorus theorem,

CK² = KM²+CM²

KM² = CK²-CM²

KM² = (41)²-(9)²

KM² = 1681-81

KM²= 1600

KM= √(1600)

KM=40

Height of ground where kite is flying = KM+MB

therefore the answer is 40+100= 140

Hope it helps!