<math display='block'> <mmlrow> <mmlsub> <mmli>T</mi> <mmli>g</mi> </msub> <mmlo>=</mo><mmlsub> <mmli>m</mi> <mmli>e</mi> </msub> <mmli>g</mi><mmlo stretchy='false'>(</mo><mmli>r</mi><mmlo>/</mo><mmln>2</mn><mmlo>&#x2212;</mo><mmli>b</mi><mmlo stretchy='false'>)</mo><mmli>cos</mi><mmli>&#x03B8;</mi> </mrow> </math>