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A room is 12m long, 9m wide and 8m high. Find the cosine of the angle which a diagonal ...

A room is 12m long, 9m wide and 8m high. Find the cosine of the angle which a diagonal of the room makes with the floor of the room
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  • A \(\frac{15}{17}\)
  • B \(\frac{8}{17}\)
  • C \(\frac{8}{15}\)
  • D \(\frac{12}{17}\)
Correct Answer: Option A
Explanation:
ABCD is the floor. By pathagoras \(^2\) = 144 + 81 = \(\sqrt{225}\) = 15cm

Height of room 8m, diagonal of floor is 15m

Therefore, the cosine of the angle which a diagonal of the room makes with the floor is
\(^2\) = 15\(^2\) + 8\(^2\) cosine

\(\frac{adj}{Hyp} = \frac{15}{17}\)
\(^2\) = \(\sqrt{225 + 64}\)
= \(\sqrt{289}\)

= 17

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