# Finding the mid point of a triangle when rotated around a specific point

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Hello

I am attempting to find the angle of a side of a right angle triangle. And also attempting to find the mid point of a right angle triangle no matter the rotation(for a webapp I am making).

I am attempting to find the angle where the question mark is, then test that my algorithm/methodology to find the position of the mid point of a shape works(this is for my HTML5 Canvas Web App).
Is my maths correct?...

// This is half code/mathematics ? = tan-1( opposite/adjacent ); // inverse tan ? = tan-1(50/25); ? = 63.43; // is that correct??

My math algorithm below attempts to find the mid point when a shape is rotated. In my webapp I will only ever know the x,y pos & the width & height, but it will also be rotated around the x,y point which means the midpoint can be different. Is it correct?

// To find the x,y midpoint all I have to do is have // the hypotenuse of the triangle & the angle of one // side(the angle I found above). Is that correct? // h stands for hypotenuse, a stands for the angle I found above midX = cos(a)*h midY = sin(a)*h // so to take the example above, if I use those formulas I should get an mid x,y value of 25,12.5 midX = cos(63.4)*75; = 33.58; // shouldn't this be 25? midY = sin(63.4)*75; = 67.06; // should be 12.5?

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Closing this so the OP can repost (he reported that this one is in error.)

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This topic is 2822 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

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