Editing Talk:2509: Useful Geometry Formulas
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add an extra edited image that is the comic without dotted lines to make it easier to see the 2d shapes? [[Special:Contributions/172.69.71.177|172.69.71.177]] 12:46, 31 August 2021 (UTC)Bampf | add an extra edited image that is the comic without dotted lines to make it easier to see the 2d shapes? [[Special:Contributions/172.69.71.177|172.69.71.177]] 12:46, 31 August 2021 (UTC)Bampf | ||
:And an animated GIF of the 3D solid objects rotating to show their real shapes. At different speeds. If you have the time. :-) Robert Carnegie [email protected] [[Special:Contributions/141.101.76.11|141.101.76.11]] 16:31, 31 August 2021 (UTC) | :And an animated GIF of the 3D solid objects rotating to show their real shapes. At different speeds. If you have the time. :-) Robert Carnegie [email protected] [[Special:Contributions/141.101.76.11|141.101.76.11]] 16:31, 31 August 2021 (UTC) | ||
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Please do check my (additional) changes to the bottom-right item (hexagon-cum-prism) in both main and transcript texts. As hinted in my edit notes, cos-theta is important because the skewed tetrahedron (rhomboid, whether in plan or the true area of the 'fake' perspective) is not d*b in area. The fact that without the theta it would look like a standard oblique orthographic projection with entirely right-angled corners is perhaps part of the (intended?) confusion, although we can probably assume that all unmarked (and, of course, uncongruent/uncomplimentary) angles are 90° so that it isn't a full on parallelepiped with an additional phi-angle on an adjacent face and a complicated third dependent-angle somewhere upon the remaining face-plane. As such, I put in the cosine element to both the 3d surface formula (it only affects the bd-shape, the both of them) and the 3d volume (from this shape, extrudes without further adjustment straight up the h-axis), but I ''always'' have to second guess if I've done this simple bit of trig right, it seems, even though I should know better and just trust to SOHCAHTOA... ;) [[Special:Contributions/162.158.158.146|162.158.158.146]] 13:24, 31 August 2021 (UTC) | Please do check my (additional) changes to the bottom-right item (hexagon-cum-prism) in both main and transcript texts. As hinted in my edit notes, cos-theta is important because the skewed tetrahedron (rhomboid, whether in plan or the true area of the 'fake' perspective) is not d*b in area. The fact that without the theta it would look like a standard oblique orthographic projection with entirely right-angled corners is perhaps part of the (intended?) confusion, although we can probably assume that all unmarked (and, of course, uncongruent/uncomplimentary) angles are 90° so that it isn't a full on parallelepiped with an additional phi-angle on an adjacent face and a complicated third dependent-angle somewhere upon the remaining face-plane. As such, I put in the cosine element to both the 3d surface formula (it only affects the bd-shape, the both of them) and the 3d volume (from this shape, extrudes without further adjustment straight up the h-axis), but I ''always'' have to second guess if I've done this simple bit of trig right, it seems, even though I should know better and just trust to SOHCAHTOA... ;) [[Special:Contributions/162.158.158.146|162.158.158.146]] 13:24, 31 August 2021 (UTC) |