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Need help with this Math exercise please

Greetings everyone, I am new to the site. I have this problem I need to program in C++:

Q:Calculate the coordinate of the point (2,3,1) after a rotation through 90deg about the x-axis.

Here is my attempt at it but I am not 100% certain this is correct, hence why I'm posting this thread:

I multiplied the 3x3 Matrix (1 0 0, 0 0 -1, 0 1 0) by the coordinates (2, 3, 1) and I obtained the following resultant matrix: [2, -1, 3]

Is my work correct? If not, please point out my mistake and give me a hint if possible, thank you.
Last edited on
Looks correct.
Now you just need to write a C++ program to this.

Tip: Instead of writing an algorithm to do matrix multiplication, just get the expression for each point.
In the future, you should post in the beginners section of this forum.
Thank you fellas.
closed account (48T7M4Gy)
Looks to be right.


1 0  0    2      2
0 0 -1    3 =   -1
0 1  0    1      3

See also https://en.wikipedia.org/wiki/Rotation_matrix
trackin bron makin plays
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