The similarity ratio of ΔABC to ΔDEF = 2 : 1.
Solution:
The image attached below.
Given ΔABC to ΔDEF are similar.
To find the ratio of similarity triangle ABC and triangle DEF.
In ΔABC: AC = 4 and CB = 5
In ΔDEF: DF = 2, EF = ?
Let us first find the length of EF.
We know that, If two triangles are similar, then the corresponding sides are proportional.
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Ratio of ΔABC to ΔDEF =
Similarly, ratio of ΔABC to ΔDEF =
Hence, the similarity ratio of ΔABC to ΔDEF = 2 : 1.
Answer:
SA = 202
Step-by-step explanation:
Surface area = Sum of all 6 areas of each side of the cuboid
SA = 2 (4·5 + 5·9 +9·4), because there are 2 of each kind of sides
SA = 2 (20+ 45 + 36)
SA = 2·101
SA = 202
(a) See the attached sketch. Each shell will have a radius <em>y</em> chosen from the interval [2, 4], a height of <em>x</em> = 2/<em>y</em>, and thickness ∆<em>y</em>. For infinitely many shells, we have ∆<em>y</em> converging to 0, and each super-thin shell contributes an infinitesimal volume of
2<em>π</em> (radius)² (height) = 4<em>πy</em>
Then the volume of the solid is obtained by integrating over [2, 4]:
(b) See the other attached sketch. (The text is a bit cluttered, but hopefully you'll understand what is drawn.) Each shell has a radius 9 - <em>x</em> (this is the distance between a given <em>x</em> value in the orange shaded region to the axis of revolution) and a height of 8 - <em>x</em> ³ (and this is the distance between the line <em>y</em> = 8 and the curve <em>y</em> = <em>x</em> ³). Then each shell has a volume of
2<em>π</em> (9 - <em>x</em>)² (8 - <em>x</em> ³) = 2<em>π</em> (648 - 144<em>x</em> + 8<em>x</em> ² - 81<em>x</em> ³ + 18<em>x</em> ⁴ - <em>x</em> ⁵)
so that the overall volume of the solid would be
I leave the details of integrating to you.
