# Gcse maths question help!

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#1
please could someone explain to me how to work the question out ASAP
Thank you so much!
(The picture is down below) x
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#2
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1 month ago
#3
You will first need to find the volume of the water that she has in the tank. It is one of the shapes you have a formula for.
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#4
(Original post by ThomH97)
You will first need to find the volume of the water that she has in the tank. It is one of the shapes you have a formula for.
There’s a formula for triangular prisms? 🤔
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1 month ago
#5
(Original post by Cherrygrape1234)
There’s a formula for triangular prisms? 🤔
Yes. For any prism the volume is:
cross sectional area x length
Last edited by 16CharsIsTooShor; 1 month ago
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#6
(Original post by 16CharsIsTooShor)
Yes. For any prism the volume is:
cross sectional area x length
Oh yeah I forgot about that thanks.
because I worked out the cross sectional area using 1/2abSinC
then multiplied it by 50cm
= 9000cm^3
= 90 litres
so if one tablet is needed for every 15 litres
then only 6 tablets will be needed for 90 litres- right?
so she has enough but I have a feeling I went wrong somewhere :/
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1 month ago
#7
(Original post by Cherrygrape1234)
Oh yeah I forgot about that thanks.
because I worked out the cross sectional area using 1/2abSinC
then multiplied it by 50cm
= 9000cm^3
= 90 litres
so if one tablet is needed for every 15 litres
then only 6 tablets will be needed for 90 litres- right?
so she has enough but I have a feeling I went wrong somewhere :/
"Once a month"
In the working there is a missing 0 and no need to use sin area formula for a right angled triangle
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#8
(Original post by mqb2766)
"Once a month"
In the working there is a missing 0 and no need to use sin area formula for a right angled triangle
I’m so confused
How are you meant to do it?
How would I work out the area without sin because isn’t it bxh/2 but I don’t know what the base is? And would the height be 50 cm?
Thank you
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1 month ago
#9
(Original post by Cherrygrape1234)
I’m so confused
How are you meant to do it?
How would I work out the area without sin because isn’t it bxh/2 but I don’t know what the base is? And would the height be 50 cm?
Thank you
In the triangle, you're allowed to choose which sides are the base and perpendicular height, as long as they're perpendicular. You have a right angle so ...

Using the sin(C) rule is not wrong here, just unnecessary. What is sin(C) when you do it?
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#10
(Original post by mqb2766)
In the triangle, you're allowed to choose which sides are the base and perpendicular height, as long as they're perpendicular. You have a right angle so ...

Using the sin(C) rule is not wrong here, just unnecessary. What is sin(C) when you do it?
I thought sin c was 90 (so I got the area to be 1800cm2)
So is the area 60 x 50 /2 = 1500cm2
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1 month ago
#11
(Original post by Cherrygrape1234)
I thought sin c was 90 (so I got the area to be 1800cm2)
So is the area 60 x 50 /2 = 1500cm2
C is 90 so sin(C)=1. When you multiply by 1 the answer is unchanged.
So you're already doing base*height/2. 1800 is correct.

What year are you in?
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#12
(Original post by mqb2766)
C is 90 so sin(C)=1. When you multiply by 1 the answer is unchanged.
So you're already doing base*height/2. 1800 is correct.

What year are you in?
Ohhhh I understand
I’m in year 11 and we are getting lots of past papers so im a bit rusty on this topic as I having dome it for a while
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#13
(Original post by mqb2766)
"Once a month"
In the working there is a missing 0 and no need to use sin area formula for a right angled triangle
Where is the missing 0 🤔
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1 month ago
#14
(Original post by Cherrygrape1234)
Where is the missing 0 🤔
Just check your calcs. Shouldn't take more than a minute.
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#15
(Original post by mqb2766)
C is 90 so sin(C)=1. When you multiply by 1 the answer is unchanged.
So you're already doing base*height/2. 1800 is correct.

What year are you in?
She goes through 6 tablets each month so that would mean 72 tablets in a year so she does have enough right?
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#16
(Original post by mqb2766)
Just check your calcs. Shouldn't take more than a minute.
I did and I still got the vol to be 90000cm3 ?
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1 month ago
#17
(Original post by Cherrygrape1234)
She goes through 6 tablets each month so that would mean 72 tablets in a year so she does have enough right?
Do you really need to check that?
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1 month ago
#18
(Original post by Cherrygrape1234)
I did and I still got the vol to be 90000cm3 ?
You posted nine thousand.
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#19
(Original post by mqb2766)
You posted nine thousand.
I think it was a typo whoops
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#20
(Original post by mqb2766)
Do you really need to check that?
Sorry I just wanted to make sure
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