Everything Maths Grade 12

10.3 CHAPTER 10. TRIGONOMETRY

Problems in 3 Dimensions EMCCP

Example 6: Height of tower

QUESTION

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�

�

D

h

A

B

C

b

θ

β

α

D is the top of a tower ofheight h. Its base is at A. The triangle ABC lies on the ground (a

horizontal plane). If wehave that BC = b, DBAˆ = α, DBCˆ = β and DCBˆ = θ, show that

h =

b sinα sinθ

sin(β +θ)

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D

h

A

B

C

b

θ

β

α

SOLUTION