Sin163°Sin223°+sin253°sin313°等于多少速度跪求

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Sin163°Sin223°+sin253°sin313°等于多少速度跪求

=sin(180°-17°)sin(180°+43°)+sin(270°-17°)sin(270°+43°)
=sin17°sin43°+cos17°cos43°
=sin(17°+43°)
=sin60°
=2分之根3

sin163°sin223°+sin253°sin313°
=sin163°sin(133°+90°)+sin(163°+90°)sin(133°+180°)
=sin163°cos133°-cos163°sin133°
=sin(163°-133°)
=sin30°
=1/2
sin163°sin223°+sin253°sin313°
=-...

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sin163°sin223°+sin253°sin313°
=sin163°sin(133°+90°)+sin(163°+90°)sin(133°+180°)
=sin163°cos133°-cos163°sin133°
=sin(163°-133°)
=sin30°
=1/2
sin163°sin223°+sin253°sin313°
=-sin17°sin43°+sin73°sin47°
=cos17°cos43°-sin17°sin43°
=cos(17°+43°)
=cos60°
=1/2

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