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Mathematics 7 Online
OpenStudy (anonymous):

Patricia has a lawn, ABCD. She has placed a watering hose, BD, as shown below. Part A: Patricia plans to put a fence along the length AD of her lawn. What is the length of the fence required? Part B: Using complete sentences, explain how you arrived at the answer for Part A.

OpenStudy (anonymous):

OpenStudy (anonymous):

@Mertsj can you help me?

OpenStudy (anonymous):

@Robb828 , do you know pythagoras theorem? a^2 + b^2 = c^2

OpenStudy (anonymous):

yes i do

OpenStudy (anonymous):

Yes, apply that and get length AD

OpenStudy (anonymous):

I mean first find BD and then find AD

OpenStudy (anonymous):

That is take triangle BCD and apply pythagoras theorem and get BD. Then take triangle ABD and apply pythagoras theorem and find AD

OpenStudy (anonymous):

so i do 30^2 + 16^2 = c^2

OpenStudy (anonymous):

yes. so get the value of c^2. Now take triangle ABD and apply sin 60 = BD / AD

OpenStudy (anonymous):

Sorry Initially I thought AD is given. But AD is not given and hence you cannot apply pythagoras theorem for ABD

OpenStudy (anonymous):

so what i got was 1156 = c^2

OpenStudy (anonymous):

Get c. Then\ sin (60) = c / AB

OpenStudy (anonymous):

you lost me...

OpenStudy (anonymous):

No I didn't c= sqrt(1156) Now sin(60) = BD/ AB Do you know trigonometry??

OpenStudy (anonymous):

not that much

OpenStudy (anonymous):

Then sin of any angle is sin(A) = opposite side to A / Hypotenuse of triangle

OpenStudy (anonymous):

Now you get it ??

OpenStudy (anonymous):

yea

OpenStudy (anonymous):

so....

OpenStudy (anonymous):

Now apply this, we get sin(60) = BD / AB we know that sin (60) = sqrt(3) / 2 BD = sqrt (1156) Apply this and and get your AB

OpenStudy (anonymous):

i got 34

OpenStudy (anonymous):

@Robb828 BD= 34 Now you know \[\sin(60) = {\sqrt{3} \over 2}\] \[{\sqrt{3} \over 2} = {34 \over AB}\] \[AB = 34 * { 2 \over \sqrt{3}}\]

OpenStudy (anonymous):

@Robb828 , make sure you practice trigonometry.

OpenStudy (anonymous):

ok thanks for you help and trust me i will lol

OpenStudy (anonymous):

yw :)

OpenStudy (anonymous):

@shivam_bhalla i forgot to ask do i multiply those last two or just leave them like that??

OpenStudy (anonymous):

@Robb828 , If you have a calcultor at home, then simplify it, else leave it that way

OpenStudy (anonymous):

*calculator

OpenStudy (anonymous):

ok i do thank you

OpenStudy (anonymous):

yw :)

OpenStudy (mertsj):

\[BD=\sqrt{30^2+16^2}=34\]

OpenStudy (mertsj):

\[AD=\frac{34}{\sqrt{3}}=\frac{34\sqrt{3}}{3}\]

OpenStudy (mertsj):

Triangle BCD is a right triangle with legs 30 and 16. Using the Pythagorean theorem I found the hypotenuse BD of that triangle. That hypotenuse BD is the long leg of the 30-60-90 right triangle BDA. AD is the short leg of that triangle. The short leg of a 30-60-90 triangle can be found by dividing the long leg by the square root of three.

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