Finding the area of trapezoid with the high and one base only.

[Zelda22]

I know the formula A= 1/2 (a + b) * h, But I only know one base and the high. I also have two coordinate points. Please help. Thanks.

I know the answer, but that doesn't help me, I need to understand how to do it. Thanks

 

[topsquark]

Either the coordinates are wrong or the height is wrong. The height is given as 660 cm but the coordinates say 979.2 cm - 900 cm = 79.2 cm.

-Dan

 

[Otis]

I also have two coordinate points.

Hi Zelda. Were those coordinates provided as part of the given exercise?

[imath]\;[/imath]

 

[Dr.Peterson]

I know the formula A= 1/2 (a + b) * h, But I only know one base and the high. I also have two coordinate points. Please help. Thanks.

I know the answer, but that doesn't help me, I need to understand how to do it. Thanks

The only way I can make sense of the coordinates is if x and y are swapped from their usual orientation and D is the origin:

​

In that case, base AB is 979.2 units.

Does that give the expected area? Does it make sense in the context of the problem?

(It would be very helpful if you told us something about where the details come from, and what the answer is that you know.)

 

[Zelda22]

The only way I can make sense of the coordinates is if x and y are swapped from their usual orientation and D is the origin:

View attachment 31901​

In that case, base AB is 979.2 units.

Does that give the expected area? Does it make sense in the context of the problem?

(It would be very helpful if you told us something about where the details come from, and what the answer is that you know.)

Here is the answer for the area. I just can't figure out how.

 

[Zelda22]

The only way I can make sense of the coordinates is if x and y are swapped from their usual orientation and D is the origin:

View attachment 31901​

In that case, base AB is 979.2 units.

Does that give the expected area? Does it make sense in the context of the problem?

(It would be very helpful if you told us something about where the details come from, and what the answer is that you know.)

I think you are right, I might swapped x and y coordinates when I rotated the trapezoid?

 

[Zelda22]

I think you are right, I might swapped x and y coordinates when I rotated the trapezoid?

Can you explain to me how to do it?

 

[Zelda22]

The only way I can make sense of the coordinates is if x and y are swapped from their usual orientation and D is the origin:

View attachment 31901​

In that case, base AB is 979.2 units.

Does that give the expected area? Does it make sense in the context of the problem?

(It would be very helpful if you told us something about where the details come from, and what the answer is that you know.)

Here is the original question, and the answer. I just can't figure it out.

 

[The Highlander]

I know the formula A= 1/2 (a + b) * h, But I only know one base and the high. I also have two coordinate points. Please help. Thanks.

I know the answer, but that doesn't help me, I need to understand how to do it. Thanks

I was just about to say the same thing as Dr.P. (but he got in first, lol ?)!

The coordinates given only make sense if the point D lies at the Origin and the original figure would have looked more like the attached pic. Then the length AB is easily established and if the figure is then rotated clockwise through 90°, you now have a Trapezium whose bases are both known and the area may be easily calculated.

Assuming our interpretation to be correct, please show us your attempt to calculate the Area of the figure (with sketch(es) & working, please).

Please always provide ALL the information you have (in its original format) in your first post on any topic (including any answers that may have been supplied with problems).

Spoiler: Answer?

Was the answer supplied: 563,760 cm²?

 

[Zelda22]

I was just about to say the same thing as Dr.P. (but he got in first, lol ?)!

The coordinates given only make sense if the point D lies at the Origin and the original figure would have looked more like the attached pic. Then the length AB is easily established and if the figure is then rotated clockwise through 90°, you now have a Trapezium whose bases are both known and the area may be easily calculated.

Assuming our interpretation to be correct, please show us your attempt to calculate the Area of the figure (with sketch(es) & working, please).

Please always provide ALL the information you have (in its original format) in your first post on any topic (including any answers that may have been supplied with problems).

Spoiler: Answer?

Was the answer supplied: 563,760 cm²?

Thank you!!!! Now it makes sense.
Thank you ALL!

 

[Dr.Peterson]

Here is the original question, and the answer. I just can't figure it out.

This is why we ask everyone to show the entire original problem they are working on! Do you see how this would have helped us?

Thank you!!!! Now it makes sense.
Thank you ALL!

 

[Zelda22]

This is why we ask everyone to show the entire original problem they are working on! Do you see how this would have helped us?

Yes, I’m sorry it was my first post. I learned my lesson. Thank you for your help.

 

[The Highlander]

Yes, I’m sorry it was my first post. I learned my lesson. Thank you for your help.

Well done, Zelda! ?

Your answer (620,136 cm²) is, of course, correct. ?

It just remains for me to add that the "answer" I provided above in my 'Spoiler' (536,760 cm²) is wrong, because I inadvertently plugged 600 (instead of 660) into my calculator when working out the area, Doh! ???

I only realized this when I saw that your (faultless) working provided a different answer from mine! (This is what happens when you rely on an ageing memory to retain numbers instead of writing them down on paper! ?)

I apologize for any confusion or consternation you (or anyone else) may have suffered as a result of my error; mea culpa! ?

Also, very pleased to see you submit your own working of the problem, so many come in and ask for our help but then don't bother to make any effort to show what they have (or have not) done. ?

 

[Zelda22]

Well done, Zelda! ?

Your answer (620,136 cm²) is, of course, correct. ?

It just remains for me to add that the "answer" I provided above in my 'Spoiler' (536,760 cm²) is wrong, because I inadvertently plugged 600 (instead of 660) into my calculator when working out the area, Doh! ???

I only realized this when I saw that your (faultless) working provided a different answer from mine! (This is what happens when you rely on an ageing memory to retain numbers instead of writing them down on paper! ?)

I apologize for any confusion or consternation you (or anyone else) may have suffered as a result of my error; mea culpa! ?

Also, very pleased to see you submit your own working of the problem, so many come in and ask for our help but then don't bother to make any effort to show what they have (or have not) done. ?

Thank you