If he goes to bed at 9:00 pm, and wakes up at 10:00 am he will have slept 13 hours.
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Step-by-step explanation:
Given :
1- cosA = 1/2
or, CosA = 1 -1/2
Therefore ; CosA = 1/2 = b/h
According to the Pythagoras theorem,
P = root under h^2 - b^2
= root under (2)^2 - (1)^2
= root under 4 -1
= root 3
Again,
SinA = P/h
= root 3 / 2