[[1]] is the angle which is four times its complement.

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Detailed Solution

Concept: 72° is the angle which is four times its complement. We'll suppose that the necessary angle is x in order to resolve this issue. Then, we will compare this to the information that is needed in this problem (that is, four times the complement of the angle). The angle x's complement is given by (90 - x).
Finding the angle that is four times its complement is necessary. So, we'll start by assuming that the angle is an x. Let y be the angle's complement. That is the total of all angles that add up to 90 degrees, according to the concept of the complement of an angle. As a result,

Additionally, we are aware that the complement is four times the angle, so we have:

From equation 1
Question Image

Hence, the correct answer is 72°.

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