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# Geometry/Pythagoras Theorem

Question

pythagoras theorem
In this image r^2=R^2+x^2(a/c to book)
but how
is the angle mentioned is right angle?
because pythagoras theorem is only for right angles as my knowledge?

The Theorem of Pythagoras is indeed only for right-angled triangles.  The picture is a three-dimensional scenario, so the angle does not look like a right angle.  If you don't look at a right angle head-on, it won't appear to be a right angle.  If you need to, draw only the xy-plane and you will see the right angle.

The angle is indeed a right angle, and the Theorem of Pythagoras can be applied.

Azeem
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Geometry

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#### Azeem Hussain

##### Expertise

I welcome your questions on algebra, 2D and 3D geometry, parabolic functions and conic sections, and any other mathematical queries you may have.

##### Experience

4 years as a drop-in and by-appointment tutor at Champlain College. Private tutor for dozens of clients over the past 8 years.

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CALPHAD: Computer Coupling of Phase Diagrams and Thermochemistry

Education/Credentials
Bachelor of Science, Major Mathematics and Major Economics, McGill University, 2014. Diploma of Collegiate Studies; Pure and Applied Science, Champlain College Saint-Lambert, 2010.