# How Can This Be? Trapezoid Angles

**URL:** <https://discourse.shapr3d.com/t/how-can-this-be-trapezoid-angles/2145>\
**Category:** Modeling Questions\
**Created:** [March 15, 2018, 9:34pm UTC](https://discourse.shapr3d.com/t/how-can-this-be-trapezoid-angles/2145 "2018-03-15T21:34:41Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![tommyn](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tommyn/32/1714_2.png) [@tommyn](https://discourse.shapr3d.com/u/tommyn)\
**Post date:** [March 15, 2018, 9:34pm UTC](https://discourse.shapr3d.com/t/how-can-this-be-trapezoid-angles/2145/1 "2018-03-15T21:34:42Z")

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I constructed a trapezoid with equal legs that does not have equal base angles. Am not nitpicking 0.1 degree. But in other tests, the angles are equal to 3 decimal places in the display. The only difference here is that the trapezoid was first drawn on a construction plane.

![image](https://cdck-file-uploads-us1.s3.dualstack.us-west-2.amazonaws.com/flex002/uploads/shapr3d/original/2X/7/75c549f351143018e5c721385fdbcde8f0e9bbea.jpeg) ![image](https://cdck-file-uploads-us1.s3.dualstack.us-west-2.amazonaws.com/flex002/uploads/shapr3d/original/2X/3/30b2a34e56656b637473ead6cfba4df10c12b7eb.jpg)

Oops, I misspoke a bit; the angles are not all exactly equal in my test case but no big deal. Including the original with all 4 angles shown FYI.

![image](https://cdck-file-uploads-us1.s3.dualstack.us-west-2.amazonaws.com/flex002/uploads/shapr3d/original/2X/d/d40a3822894129563631531f251d2774ec5512c7.jpg) ![image](https://cdck-file-uploads-us1.s3.dualstack.us-west-2.amazonaws.com/flex002/uploads/shapr3d/original/2X/3/3f55898529676ff88f7b307c1d64bee7d7ed70ad.jpg)

Thanks,

Tommy

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**Author:** ![Koko\_Shapr3D](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/koko_shapr3d/32/1703_2.png) [@Koko\_Shapr3D](https://discourse.shapr3d.com/u/Koko_Shapr3D)\
**Post date:** [March 16, 2018, 9:18am UTC](https://discourse.shapr3d.com/t/how-can-this-be-trapezoid-angles/2145/2 "2018-03-16T09:18:28Z")

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You should add horizontal/vertical constraints to the top and the bottom side. (Or a parallel constraint between them.) Otherwise, it is just a quadrilateral with two equal sides, not a trapezoid.

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**Author:** ![tommyn](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tommyn/32/1714_2.png) [@tommyn](https://discourse.shapr3d.com/u/tommyn)\
**Post date:** [March 16, 2018, 7:10pm UTC](https://discourse.shapr3d.com/t/how-can-this-be-trapezoid-angles/2145/3 "2018-03-16T19:10:17Z")

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Thank you for your responsiveness. Somehow I thought a line snapping to a grid would auto-insure horizontal/parallel condition. I guess being explicit is always best.

Tommy

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**Author:** ![Koko\_Shapr3D](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/koko_shapr3d/32/1703_2.png) [@Koko\_Shapr3D](https://discourse.shapr3d.com/u/Koko_Shapr3D)\
**Post date:** [March 16, 2018, 7:56pm UTC](https://discourse.shapr3d.com/t/how-can-this-be-trapezoid-angles/2145/4 "2018-03-16T19:56:30Z")

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Yes, you are right. The expected behavior here is that (due to snapping) those lines are horizontal. We will look into this. Thank you for the report.

However, it is always better to constrain everything that you expect to be constrained, especially if you use other constraints.