sin7.5°的值
邱武薛2789利用和(差)角公式,求sin75°的值为 - ----- -
贲姜具17187629183 ______ sin75°=sin(45°+30°)=sin45°cos30°+cos45°sin30°= 2 2 ? 3 2 + 2 2 ? 1 2 = 2 + 6 4 故答案为: 2 + 6 4
邱武薛2789 sin 15°cos30°sin75° 的值等于 ( ) A. B . C. D. -
贲姜具17187629183 ______[答案] 答案:B提示:∵sin75°=cos15° ∴原式=sin15°cos15°cos30°=sin30°cos30°=sin60°=.
邱武薛2789sin750度的三角函数值 -
贲姜具17187629183 ______[答案] sin 750°=sin 30°=0.5
邱武薛2789cos7.5°等于多少? -
贲姜具17187629183 ______[答案] cos15°=cos(45°-30°) =cos45°cos30°+sin45°sin30° =(√6+√2)/4 cos²7.5° =(1+cos15°)/2 =[1+(√6+√2)/4]/2 =1/2+(√6+√2)/8 在开方就行了
邱武薛2789笔算sin、cos、tan值.比如说sin75度等于多少啊,要全面点的大神们帮帮忙 -
贲姜具17187629183 ______[答案] sin75°=sin(45+30)° =sin45°cos30°-cos45°sin30° =√2/2(√3/2-1/2)
邱武薛2789sin15°sin30°sin75°的值等于? -
贲姜具17187629183 ______[答案] sin15sin30sin75 =(1/2)sin15sin(90-15) =(1/2)sin15cos15 =(1/2)*[(1/2)*2sin15cos15] =(1/4)sin30 =1/8
邱武薛2789 sin15°sin75°的值是______. -
贲姜具17187629183 ______[答案] ∵sin15°sin75° =sin15°cos15° =12sin30° =14. ∴sin15°sin75°的值是14. 故填:14.
邱武薛2789sin15°、sin75°的值分别是多少用含有根号的式子表示 -
贲姜具17187629183 ______[答案] sin15=sin(45-30)=sin45cos30-cos45sin30=√2/2*√3/2-√2/2*1/2=(√6-√2)/4sin75=sin(45+30)=sin45cos30+cos45sin30=√2/2*√3/2+√2/2*1/2=(√6+√2)/4
邱武薛2789 sin15°sin30°sin75°的值等于( )ؤ ث A.ث B.ث C.ث D.ث -
贲姜具17187629183 ______[答案] Cثإ 解析:原式 = sin(45°-30°)sin(45°+30°)= (sin45°cos30°-cos45°sin30°)(sin45°cos...
邱武薛2789sin70°sin65° - sin20°sin25° 的 值 是多少 -
贲姜具17187629183 ______[答案] 解 sin70sin65-sin20sin25 =sin70cos25-cos70sin25 =sin(70-25) =sin(45) =√2/2