Answer:
•cos(s+t) = cos(s)cos(t) - sin(s)sin(t) = (-⅖).(-⅗) - (√21 /5).(⅘) = +6/25 - 4√21 /25 = (6-4√21)/25
•cos(s-t) = cos(s)cos(t) + sin(s)sin(t) = (-⅖).(-⅗) + (√21 /5).(⅘) = +6/25 + 4√21 /25 = (6+4√21)/25
cos(t) = ±√(1 - sin²(t)) → -√(1 - sin²(t)) = -√(1 - (⅘)²) = -⅗
sin(s) = ±√(1 - cos²(s)) → +√(1- cos²(s)) = +√(1 - (-⅖)²) = √21 /5
= 4i (2i) <span>√6
= 8i^2 </span><span>√6 but i^2 = -1
= - 8</span><span>√6</span><span>
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A would be your answer
Hope this helps !!
The birth weight of elephants at the 85th percentile is 262.16 pounds
<h3>What is the standard deviation?</h3>
Standard deviation is defined as the amount of variation or the deviation of the numbers from each other.
Given that:-
The average birth weight of elephants is 200 pounds
= 200
The deviation of 60 pounds.
= 60
The birth weight of elephants at the 85th percentile. z = 85%= 1.036
Now from the formula of z-score:-

Hence the birth weight of elephants at the 85th percentile is 262.16 pounds
To know more about standard deviation follow
brainly.com/question/475676
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