Which statement is true?
1 answer:
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Answer:
The three angles of the triangle are 90, 35.67 and 54.33 degrees.
Step-by-step explanation:
One way to find the angles of the triangle with vertices (1, 1, 1), (1, -3, 2), (-3, 2, 5) is using the definition of the <em>dot product</em> of two vectors, defined as:
a . b = |a| |b| cosФ [1]
Where |a| and |b| are the norms of vectors <em>a</em> and b, and cosФ is the cosine of the angle between either vector <em>a</em> and <em>b</em>.
If a = [ ] and b = [
], then the dot product is simply a number (not a vector) obtained from:
a . b =
The norm of a vector (its length) is, for instance, |a| = , for a vector in
.
Having all that into account, we can determine the angles of the triangle for each vertex using equation [1] and solving it for Ф.
<h3>Angle of the triangle for vertex in (1, 1, 1)</h3>The vectors which form an angle from this vertex are the result of subtracting the vertex (1, 1, 1) to any of the remaining points (1, -3, 2) and (-3, 2, 5):
v(1, 1, 1) - v(1, -3, 2) =
v(1, 1, 1) - v(-3, 2, 5) =
The <em>dot product</em> for these vectors is:
[0, 4, -1] . [4, -1, -4] = [0 * 4 + 4 * -1 + -1 * -4] = 0 - 4 + 4 = 0
The norm for each vector is:
|(0, 4, -1)| =
|(4, -1, -4)| =
So
a . b = |a| |b| cosФ
In vertex (1, 1, 1) the angle of the triangle is 90 degrees. We have here a right triangle.
We have to follow the same procedure for finding the vectors for angles in vertices (1, -3, 2) and (-3, 2, 5), or better, after finding one of the previous angles, we find the remaining angle subtracting the sum of two angles from 180 degrees to finally obtaining the three angles in question.
Therefore, the other angles are 35.67 degrees and 180 - (90 + 35.67) = 180 - 125.67 = 54.33 degrees.
Complete Question:
A soft-drink vendor at a popular beach analyzes his sales records, and finds that if he sells x cans of soda pop in one day, his profit (in dollars) is given by P(x) = -0.001x² + 3x - 1800.
a. What is his maximum profit per day?
b. How many cans must be sold in order to obtain the maximum profit?
Answer:
a. $450
b. 1500 cans
Step-by-step explanation:
Given the following quadratic function;
P(x) = -0.001x² + 3x - 1800 ......equation 1
a. To find his maximum profit per day;
Since P(x) is a quadratic equation, P(x) would be maximum when
Note : the standard form of a quadratic equation is ax² + bx + c = 0 ......equation 2
Comparing eqn 1 and eqn 2, we have;
a = -0.001, b = 3 and c = -1800
Now, we determine the maximum profit;
Substituting the values, we have;
Cancelling out the negative signs, we have;
x at maximum = 1500
Substituting the value of "x" into equation 1;
P(1500) = -0.001 * 1500² + 3(1500) - 1800
P(1500) = -0.001 * 2250000 + 4500 - 1800
P(1500) = -2250 + 2700
P(1500) = $450
b. Therefore, the soft-drink vendor must sell 1500 cans in order to obtain the maximum profit.