作业帮(cos^2 10°-cos^2 80°)+sin^2 20°
来源：学生作业帮助网 编辑：作业帮 时间：2024/04/30 03:17:41
(cos^2 10°-cos^2 80°)+sin^2 20°
(cos^2 10°-cos^2 80°)+sin^2 20°
(cos^2 10°-cos^2 80°)+sin^2 20°
(cos^2 10°-cos^2 80°)²+sin^2 20°
=(cos^2 10°-sin^2 10°)²+sin^2 20°
=cos²20＋sin²20°
=1