sin cos tan cot
1 sec^4 - sec² 化簡成 1/cot4 1/cot²
2 sec/cos - tan/cot 化簡成 1
3 (1-2cos²)/(sincos) 化簡成 tan - cot網友廻答：
- 1.sec^4 - sec² =1/cos^4-1/cos^2=
（1-cos^2）/cos^4=sin^2/cos^4=(sin^4 sin^2-sin^4)/cos^4
=sin^4/cos^4 (sin^2-sin^4)/cos^4
=tg^4 sin^2*cos^2/cos^4
=1/cot^4 sin^2/cos^2=1/cot^4 1/cot^2
2.sec/cos - tan/cot =1/cos^2-sin^2/cos^2
=cos^2/cos^2=1
3.(1-2cos^2)/(sincos) =(sin^2 cos^2-2cos^2)/sincos
=(sin^2-cos^2)/sincos=sin^2/sincos-cos^2/sincos
=sin/cos-cos/sin=tan - cot
網友廻答：
- sin^2 cos^2=11.sec^4-sec^2=(1/cos^4)-1/(cos^2)=(sin^2)/(cos^4)=[(sin^2)*(sin^2 cos^2)]/cos^4=1/cot4 1/cot²2.sec/cos - tan/cot=1/(cos^2)-(sin^2)/(cos^2)=cos^2/cos^2=13.(1-2cos²)/(sincos) =(...
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