(3/sin^20)-(1/cos^20)+64sin^20 =[3(cos20)^2-(sin20)^2]/(sin20)^2(cos20)^2+64(sin20)^2 =[(√3cos20+sin20)(√3cos20-sin20)]/(sin20cos20)^2+64(sin20)^2 =[2sin(60+20)*2sin(60-20)]/[(sin40)/2]^2+64(sin20)^...