![](https://static.wixstatic.com/media/3a6acb_8ad09183b4524398ad0bda7df6ca5042~mv2.jpg/v1/fill/w_250,h_250,fp_0.50_0.50,q_30,blur_30,enc_auto/3a6acb_8ad09183b4524398ad0bda7df6ca5042~mv2.jpg)
![0080// What is the difference between A parallel to B and B parallel to A ?](https://static.wixstatic.com/media/3a6acb_8ad09183b4524398ad0bda7df6ca5042~mv2.jpg/v1/fill/w_319,h_240,fp_0.50_0.50,q_90,enc_auto/3a6acb_8ad09183b4524398ad0bda7df6ca5042~mv2.jpg)
0080// What is the difference between A parallel to B and B parallel to A ?
In math, you can confidently say that, A parallel to B same as B parallel to A. However, in GD&T perspective, this is not the case. Why?
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![0012// Tangent Planes](https://static.wixstatic.com/media/3a6acb_76004beea5534453af0b04b840a03dce.jpg/v1/fill/w_149,h_59,fp_0.50_0.50,q_90,enc_auto/3a6acb_76004beea5534453af0b04b840a03dce.jpg)
0012// Tangent Planes
In some cicumstances, functional requirement of the part/components only require geometrical characteristic of feature's tangent planes...