Question

A 720 meters long train crosses a man in 60 second what would be the speed of the train​

Answer 1

⇢Question:-

sin²5 + sin²10 + sin²15 + ••• + sin²85° + sin²(90°) =?

⚘Answer:-

$\large\displaystyle \red{ { \rm{{\lim_{n \to \infty } {e}^{ - n} \sum_{ \mathbb{k = 0}}^{n} \frac{ {n}^{ \mathbb{k}} }{ \mathbb{k!}} }}}}$

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⚘Explanation:-

ㅤㅤㅤ⇢ sin θ = cos (90° – θ)

ㅤㅤㅤ⇢ sin (90° – θ) = cos θ

ㅤㅤㅤㅤ∴ sin 85° = sin (90° – 5°) = cos 5°

ㅤㅤㅤㅤ∴ (sin² 5° + sin² 85°) + (sin² 10° + sin² 80°) + •••• ㅤㅤㅤㅤㅤto 8 terms + sin² 45° + sin² 90°

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ㅤㅤㅤㅤ⚘⇢ So, your answer was 9×1/2

Answer 2

Answer:

Distance covered by train = length of train +length of platform

So distance = 170

Time = 60 seconds

Speed = distance/time

= 170/60

=2.8334m/sec

In km/h

=2.8334×60×60/1000

=10.20024 km/h

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