Charmish Kaneria
Last Activity: 7 Years ago
sina=msinbor, m=sina/sinb ---------(1) andtana=ntanbor, sina/cosa=n(sinb/cosb)or, n=sinacosb/cosasinbor, n=m (cosb/cosa) -----(2)or, ncosa=mcosbor, n²cos²a=m²cos²bor, n²cos²a=m²(1-sin²b) [∵, sin²a+cos²a=1]or, n²cos²a=m²(1-sin²a/m²) [using (1)]or, n²cos²a=m²{(m²-sin²a)/m²}or, n²cos²a=m²-sin²aor, n²cos²a=m²-(1-cos²a)or, n²cos²a=m²-1+cos²aor, n²cos²a-cos²a=m²-1or, cos²a(n²-1)=m²-1or, cos²a=(m²-1)/(n²-1)