Keyhole Concept Question

[tjung789]

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Hi,

I'm having a really hard time with keyholes. I have attached a problem (the answer is A). I put that the answer was B. Is the reason B is wrong, is because if we slid it through the keyhole of B, the pointy thing of the hexagon would still be sticking out and there is no real way to slide that pointy thing through, because the rest of the object is already passed through?

Please let me know whether my chain of reasoning is correct and/or if you have a better reason for why A is correct and B is wrong. I'd really like to know why B is wrong?

Thanks!

 

[bawby13]

Hi tjung,

Don't give up! You're asking about some of the harder achiever keyholes so you're probably in better shape than you think (always remember Achiever is supposed to make you feel a bit worse).

Onto the problem - so B is really testing your ability to discern proportions. This is something you just have to learn to develop (actual perceptual ability). A good tool or way to do this is by visualizing planes on the 3D object. I drew on your image to show you what I'm talking about (hope you don't mind!):

As you can see, the right-most extension at the end should not be extending past bottom extension from the hexagon. Thus, B, is incorrect.

Obviously, since you don't have MSPaint on game day, try using your mouse (and a steady hand that can draw straight lines) to outline planes that will help determine if that one extension/protrusion is longer/shorter than another one. It's all about planes! Hope this helps.