Answer:
≈ 30.63 cm²
Step-by-step explanation:
The shaded area is calculated by subtracting the area of the inner circle from the area of the outer circle.
outer circle has radius = 8 ÷ 2 = 4 and inner circle has radius = 5 ÷ 2 = 2.5
shaded area = πr₁² - πr₂² (r₁ is outer and r₂ is inner )
A = π (4² - 2.5²)
= π(16 - 6.25) = 9.75π ≈ 30.63 cm²
Answer: 1.303639
Step-by-step explanation:
The t-score for a level of confidence
is given by :_
, where df is the degree of freedom and
is the significance level.
Given : Level of significance : 
Then , significance level : 
Sample size : 
Then , the degree of freedom for t-distribution: 
Using the normal t-distribution table, we have

Thus, the t-score should be used to find the 80% confidence interval for the population mean =1.303639
Answer:
Validation
Step-by-step explanation: Validation is a term used to describe the processes involved when we compare a set of values and observations against a set standard or rules to ensure that they meet certain expectations or criteria.
Validation is meant to prove that something, a data set etc are acceptable based on known rules, the rules or standards which is used to evaluate what can be described as valid.
The angle that is coterminal to 425° is the last one:
B = 425° + n*1,440°
<h3>Which measure is of an angle that is coterminal with a 425° angle?</h3>
By definition, for any angle A, we can say that an angle B is coterminal to A if:
B = A + n*360°
where n can be any integer.
So, from the given options, we need to see which one is a multiple of 360°.
Of the given options, the only that meets this condition is the last one:
B = 425° + n*1,440°
Where:
1,440°/360° = 4
Then we conclude that:
425° + n*1,440° is coterminal to 425°.
If you want to learn more about coterminal angles:
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The height of the tree is the sum of the part below the line parallel to the horizontal and the part above the line parallel to the horizontal.
Height of the part below the line parallel to the horizontal = 18 sin16° = 4.96 meters
Horizontal distance of the tip of the of the shadow from the tree = 18 cos16° = 17.30 meters
Height of the part above the line parallel to the horizontal = 17.3 tan68° = 42.83 meters
Height of the tree = 4.96 + 42.83 = 47.79 meters