第1个回答 2023-10-23
解:
sin15°
=sin(45°-30°)
=sin45°cos30°-cos45°sin30°
=√2/2×√3/2-√2/2×1/2
=(√6-√2)/4
cos15°
=cos(45°-30°)
=cos45°cos30°+sin45°sin30°
=√2/2×√3/2+√2/2×1/2
=(√6+√2)/4
tan15°
=tan(45°-30°)
=(tan45°-tan30°)/(1+tan45°tan30°)
=(1-√3/3)/(1+√3/3)
=(1-√3/3)²/[(1+√3/3)(1-√3/3)]
=(4/3-2√3/3)/(2/3)
=2-√3本回答被网友采纳