Pleasee help mee12sin(x)-5cos(x)=6,5

Mathematics

1 answer:

abruzzese [7]2 years ago

3 0

We turn -5,12 into polar coordinates. It's a Pythagorean Triple so

r = 13 Ф=arctan(-12/5) + 180° ( in the second quadrant )

so -5 = 13 cos Ф, 12 = 13 sin Ф

12 sin x - 5 cos x = 6.5

13 sinФ sin x + 13 cos Ф cos x = 6.5

13 cos(x - Ф) = 6.5

cos(x - Ф) = 1/2

cos(x - Ф) = cos 60°

x - Ф = ± 60° + 360° k integer k

x = Ф ± 60° + 360° k

x = 180° + arctan(-12/5) ± 60° + 360° k

That's the exact answer;

x ≈ 180° - 67.38° ± 60° + 360° k

x ≈ 122.62° ± 60° + 360° k

x ≈ { 62.62°, 182.62°} + 360° k, integer k

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Answer:

Weights of at least 340.1 are in the highest 20%.

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

$\mu = 330, \sigma = 12$