Question

An aero plane flying horizontally 1 km above the ground is observed at an elevation of 60". After 10 seconds, its
elevation is observed to be 30". Find the speed of the aeroplane in km/hr.
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Answer 1

$\huge\mathbb{Hello!}$ Here's $\huge\mathbb{Answer}$Tan60°= 1/d =√3

⇒d =1/√3 km 

now, the aeroplane cover (d+x) km

tan30°= 1/(d+x)=1/√3

⇒(d+x) = √3

⇒x = √3 -(1/√3) = (3-1)/√3 =2/√3= (2×1.732)/3 = 1.15 km

so speed =distance/time = 1.15/(10/3600) =414 km/hr $\huge\mathbb{Thank-you!}$❤️