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how would you do this?

would it be right to assume that this is a 3,4,5 triangle or is there a more logical approach?Capture3.PNG
Original post by sara.f05
would it be right to assume that this is a 3,4,5 triangle or is there a more logical approach?Capture3.PNG

Pythagoras. You'll need two right-angled triangles - can you see where?
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sara.f05
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Original post by RogerOxon
Pythagoras. You'll need two right-angled triangles - can you see where?

yes, i tried using pythagoras with lengths 5 squared - 3.5 squared but i had an incorrect answer. this is a non-calculator paper
Original post by sara.f05
yes, i tired using pythagoras with lengths 5 squared - 3.5 squared but i had an incorrect answer. this is a non-calculator paper

Hint: The perpendicular distance from the centre to the top and bottom horizontal lines isn't the same.

You don't need a calculator. I did it without writing or drawing anything.
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sara.f05
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Original post by RogerOxon
Hint: The perpendicular distance from the centre to the top and bottom horizontal lines isn't the same.

You don't need a calculator. I did it without writing or drawing anything.

still a bit confused :confused:

update: i did 5 squared - 4 squared and got the correct answer, just not sure where the 4 came from as the top line and bottom line are not the same in length.
(edited 3 years ago)
Original post by sara.f05
still a bit confused :confused:

update: i did 5 squared - 4 squared and got the correct answer, just not sure where the 4 came from as the top line and bottom line are not the same in length.

Draw a right-angled triangle with the centre, mid-point and one end of the top horizontal line. That's a 3, 4 (half the horizontal line's length), 5 (radius) triangle, so tells you that the centre is 3cm down from the top horizontal line. Therefore, it's 7-3=4cm up from the lower one. Now draw another right-angled triangle to calculate half the bottom horizontal line's length.
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sara.f05
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Original post by RogerOxon
Draw a right-angled triangle with the centre, mid-point and one end of the top horizontal line. That's a 3, 4 (half the horizontal line's length), 5 (radius) triangle, so tells you that the centre is 3cm down from the top horizontal line. Therefore, it's 7-3=4cm up from the lower one. Now draw another right-angled triangle to calculate half the bottom horizontal line's length.

thank you! i understand it now:smile:

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