 ## Question

Secondary 1 | Maths

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##### SlyFox

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Help needed. Thanks!

Date Posted: 8 months ago
Views: 57

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Date Posted: 8 months ago
SlyFox
8 months ago
I dont understand how AB could be the height of the triangle and parallelogram. Shouldnt the base of the triangle (BE) and the base of the parallelogram (BC) be perpendicular to AB (h) in order for AB to be classified as the height of the triangle and parallelogram? Many thanks.
LIM TENG SHUEN ERNEST
8 months ago
AB is not the same as h. For triangle area calculations we need to let h be the perpendicular height, where h is some unknown value. We then calculate from there.

AB is the length of the side of the parallelogram, which is obviously not perpendicular to BE, so we can't use it for area calculations.
SlyFox
8 months ago
So basically, we do not need to know where h is? Can we just assume that there is a same height perpendicular to both the triangle and the parallelogram? Or do we have to find out the height that is perpendicular to both the triangle and the parallelogram, and name it ‘h’? Many thanks.
LIM TENG SHUEN ERNEST
8 months ago
Based on the diagram you drew, assuming it is correct, if BE is the base of the triangle, it's top point A touches the top of the parallelogram AD. This means the height of the triangle ABE and the height of the parallelogram (with base BC) must be the same value.

I did my calculations based on the diagram you drew. I didn't need to assume that the height of ABE and the height of ABCD are the same - the diagram shows that they ARE the same.
SlyFox
8 months ago
So where exactly is “h”? h must be perpendicular to both the base of triangle (BE) and base of parallelogram (BC) right? I can’t seem to find where the line ‘h’ is
LIM TENG SHUEN ERNEST
8 months ago
Yes, h is not indicated in the diagram you drew originally, we need to draw it in ourselves to help us visualize and calculate.

Draw a line perpendicular to BC that touches the line AD. The length of that new line is "h"
SlyFox
8 months ago
I fully understand it now. Thank you sooooo much!!!!!!!!!!!! 