<u>Answer:</u>
<em>Rigel and Betelgeuse </em>
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<u>Explanation:</u>
Rigel and Betelgeuse are counted in the brightest stars of the galaxy.
They form a pair in the Orion constellation.
The Rigel star is situated near the Equator. This star is invisible in the region around and above of latitude 82°N and can be seen from any part of the world. It is a blue white giant star. This makes Rigel helpful in navigation.
Betelgeuse is a red giant star which is visible from naked eye. It has the same diameter as that of Jupiter.
The circle has two forms of equation - General Form and Standard Form. The general form of the equation of the circle would be x^2 + y^2 + Dx + Ey + F = 0. The constants of this equation are D , E and F. The way to use general form is to complete the square and then proceed the equation in standard form. In that way we can identify the radius and center of the given circle.