tanA-sinA =x
tanA+sinA =y
প্রমাণ করতে হবে যে,
(x2-y2)2= 16xy
বা, {(tanA - sinA)2_ ( tanA + sinA)2}2 = 16(tanA+sinA)(tanA-sinA)
L.H.S = (x2-y2)2
= {(tanA - sinA)2_ ( tanA + sinA)2}2
= {(tanA- sinA+ tanA+ sinA)(tanA- sinA- tanA- sinA)}2
= {( 2tanA)(- 2sinA)}2
= (-4tanAsinA)2
= 16(tanAsinA)2
= 16(tan2A.sin2A)
= 16 (tan2A(1- cos2A)}
= 16 (tan2A- tan2A.cos2A)
= 16 ( tan2A- sin2A)
= 16 (tanA+sinA)(tanA-sinA)
সুতরাং, L.H.S=R.H.S [PROVED]