| A clock tower stands at the crossing of two roads which point in the north-south and the east-west directions. P, Q, R and S are points on the roads due north, east, south and west respectively, where the angles of elevation of the top of the tower are respectively, α, β, γ and δ. Then 
is equal to:
is equal to:A. 
B. 
C. 
D. 
Right Answer is: B
SOLUTION
Let OA be straight tower.
P, Q, R and S are points on the roads due north, east, south and west
respectively.
In Δ POQ and Δ ORS
So 
∠ AOQ = 90° ……….. as OA is straight tower.
∠ AOP = 90° = ∠ AOR = ∠ AOS
Now Angle of elevation are α, β, γ and δ.
In right angle Δ AOP:
And ∠ APO = α
Tanα = AO/OP
OP = AO cotα
Similarly, in Δ AOS:
∠ AOS = 90° and ∠ ASO = δ
Tanδ = AO/OS
OS = OA cotδ
And OQ = AO cotβ
And OR = AO cot γ
So, the value
