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Key Equations

# Key Equations

 Kepler’s third law $T12T22=r13r23T12T22=r13r23$ eccentricity $e=fae=fa$ area of an ellipse $A=πabA=πab$ semi-major axis of an ellipse $a=(ra+rp)/2a=(ra+rp)/2$ semi-minor axis of an ellipse $b=rarpb=rarp$
 Newton’s second law of motion $F=ma=mgF=ma=mg$ Newton’s universal law of gravitation $F=GmMr2F=GmMr2$ acceleration due to gravity $g=GMr2g=GMr2$ constant for satellites orbiting the same massive object $r3T2=GM4π2r3T2=GM4π2$