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Geometry 21 Online
OpenStudy (loner2345):

I need help please! MEDAL AND FAN. Photo will be in the comments. 1A.) Draw an right triangle inside the rectangle so that the area of the triangle is 1/4 the area of the rectangle. Position one side of the triangle along one side of the rectangle. 1B.) Explain how you know that the area of your triangle is 1/4 the area of the rectangle.

jhonyy9 (jhonyy9):

how you think it ? try drawing it

OpenStudy (loner2345):

I did and I have gotten it wrong every time

jimthompson5910 (jim_thompson5910):

It sounds like you're already given a drawing of a rectangle?

OpenStudy (loner2345):

jimthompson5910 (jim_thompson5910):

one way is to draw a right triangle where 2 of the legs lie along the rectangle sides one leg is exactly equal to the length of the rectangle (bottom side) the other leg of the triangle is half as long as the height see attached to look at the red triangle I drew. This red triangle has exactly 1/4 of the area of the rectangle

OpenStudy (loner2345):

Okay so now what to I do? @jim_thompson5910

jimthompson5910 (jim_thompson5910):

that wraps up part A. You now need to explain why this works in part B

jimthompson5910 (jim_thompson5910):

do you see why this works?

OpenStudy (loner2345):

Isn't because now both parts of the rectangle are the same? @jim_thompson5910

jimthompson5910 (jim_thompson5910):

if the base is x and the height is y, then what is the area of the rectangle?

OpenStudy (loner2345):

I have am not sure...... @jim_thompson5910

jimthompson5910 (jim_thompson5910):

the area would be base*height = x*y, no?

jimthompson5910 (jim_thompson5910):

I'm referring to the rectangle

OpenStudy (loner2345):

Oh I see now, so I would say use formula A=bh?

OpenStudy (loner2345):

@jim_thompson5910

OpenStudy (loner2345):

and the other part c, it says suppose a grain of sand randomly falls onto your drawing. What is the probability that it lands on the right triangle? @jim_thompson5910

jimthompson5910 (jim_thompson5910):

so the area of the rectangle is x*y what is the area of the triangle? base of triangle = x height of triangle = y/2

OpenStudy (loner2345):

x and y are both 1/4 right?

OpenStudy (loner2345):

@jim_thompson5910

jimthompson5910 (jim_thompson5910):

no, x and y are unknowns really

jimthompson5910 (jim_thompson5910):

if the base is x and the height is y/2, then we plug them into b*h/2 b*h/2 = x*y/2*(1/2) = x*y/4 agreed?

OpenStudy (loner2345):

Okay, my partner on this assignment said they were both 1/4

OpenStudy (loner2345):

Yes agreed

jimthompson5910 (jim_thompson5910):

so the rectangle has area x*y the red triangle has area x*y/4

jimthompson5910 (jim_thompson5910):

this shows that the triangle area is 1/4 of the rectangle area

OpenStudy (loner2345):

Okay now I get it thank you. And did you see the part c up a ways in the comments

jimthompson5910 (jim_thompson5910):

`and the other part c, it says suppose a grain of sand randomly falls onto your drawing. What is the probability that it lands on the right triangle? ` the triangle has 1/4 of the area of the rectangle, so the chances of it landing in the triangle is 1/4 = 0.25 = 25%

jimthompson5910 (jim_thompson5910):

if you want hard numbers, then say the rectangle is 20 by 5 base = 5 height = 20 area of rectangle = 5*20 = 100 square units the triangle would be 10*5/2 = 50/2 = 25 square units 25/100 = 1/4 is the probability of landing on the triangle

OpenStudy (loner2345):

Thank you so much! could you help me with the other parts please?

jimthompson5910 (jim_thompson5910):

which other part?

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