Answer:
<u>For the first answer (A)</u>
The area of the base is the area of the 8 by 4 rectangle, minus the missing 2 by 2 square in the top-right. This is 8*4-2*2=32-4=28 square centimeters.
<u>For the second answer (B)</u>
The volume of the prism is the base area multiplied by the height, or 28*10=280 cubic centimeters.
A = l × w. Substitute 72 into A and fill in the rest of the equation.
w = l - 1. Plug l - 1 into w
72 = l × (l - 1). Multiply l by (l - 1)
72 = l^2 - l. Subtract 72 from each side.
0 = l^2 - l - 72. Factor.
0 = (l + 8) (l - 9). Set each term equal to zero.
(l + 8) = 0. Subtract 8 from each side.
l = -8. Length cant be a negative number so let's try the other term.
(l - 9) = 0. Add 9 to each side.
l = 9. The length is 9.
Earlier we stated that the width is one less than the length, therefore, the width is 9 - 1 = 8.
The width is 8 units.
<h3>
Answer: A. 18*sqrt(3)</h3>
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Explanation:
We'll need the tangent rule
tan(angle) = opposite/adjacent
tan(R) = TH/HR
tan(30) = TH/54
sqrt(3)/3 = TH/54 ... use the unit circle
54*sqrt(3)/3 = TH .... multiply both sides by 54
(54/3)*sqrt(3) = TH
18*sqrt(3) = TH
TH = 18*sqrt(3) which points to <u>choice A</u> as the final answer
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An alternative method:
Triangle THR is a 30-60-90 triangle.
Let x be the measure of side TH. This side is opposite the smallest angle R = 30, so we consider this the short leg.
The hypotenuse is twice as long as x, so TR = 2x. This only applies to 30-60-90 triangles.
Now use the pythagorean theorem
a^2 + b^2 = c^2
(TH)^2 + (HR)^2 = (TR)^2
(x)^2 + (54)^2 = (2x)^2
x^2 + 2916 = 4x^2
2916 = 4x^2 - x^2
3x^2 = 2916
x^2 = 2916/3
x^2 = 972
x = sqrt(972)
x = sqrt(324*3)
x = sqrt(324)*sqrt(3)
x = 18*sqrt(3) which is the length of TH.
A slightly similar idea is to use the fact that if y is the long leg and x is the short leg, then y = x*sqrt(3). Plug in y = 54 and isolate x and you should get x = 18*sqrt(3). Again, this trick only works for 30-60-90 triangles.
Answer: Hi there, the answer should be the third option v < -8.
She uses four pounds because 4/5 of five pounds is four.
