Abcd is rotated counterclockwise about the origin. by how many degrees was abcd rotated?

90°

To get the angle of rotation, take a point for instance A, and join it to the center. Join the image of A, A', to the origin, O, also.

Then measure the angle AOA' with O as your center. The rotation can be clockwise or anticlockwise which is also known as counter clockwise.

This can be done with all other points and the angle of rotation will be the same.

For the question above, when this is done and the angle is measured counterclockwise, it will be found to be 90°

∴ AOA' = 90°

BOB' = COC' = DOD' = 90°

in mathematics, a function is a relationship between two variables such that the value of one of the variables, called the dependent variable, is determined by the value of the other variable, called the independent variable. there is a specific term we use to describe the set of independent variables of a function.

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