回答:
说明:
我们必须采取双方的正弦或余弦。专业提示:选择余弦。这可能没关系,但这是一个很好的规则。
所以我们将面临
这是正弦角度的余弦
现在让我们来解决问题吧
我们有一个
校验:
让我们这次采取正义。
显然,arccos的正主要值导致正正弦。
什么是(sqrt(5+)sqrt(3))/(sqrt(3+)sqrt(3+)sqrt(5)) - (sqrt(5-)sqrt(3))/(sqrt(3+)sqrt (3-)SQRT(5))?
2/7我们采取,A =(sqrt5 + sqrt3)/(sqrt3 + sqrt3 + sqrt5) - (sqrt5-sqrt3)/(sqrt3 + sqrt3-sqrt5)=(sqrt5 + sqrt3)/(2sqrt3 + sqrt5) - (sqrt5 -sqrt3)/(2sqrt3-sqrt5)=(sqrt5 + sqrt3)/(2sqrt3 + sqrt5) - (sqrt5-sqrt3)/(2sqrt3-sqrt5)=((sqrt5 + sqrt3)(2sqrt3-sqrt5) - (sqrt5-sqrt3) )(2sqrt3 + sqrt5))/((2sqrt3 + sqrt5)(2sqrt3-sqrt5)=((2sqrt15-5 + 2 * 3-sqrt15) - (2sqrt15 + 5-2 * 3-sqrt15))/((2sqrt3) ^ 2-(sqrt5)^ 2)=(取消(2sqrt15)-5 + 2 * 3cancel(-sqrt15) - 取消(2sqrt15)-5 + 2 * 3 +取消(sqrt15))/(12-5)=( -10 + 12)/ 7 = 2/7请注意,如果在分母中(sqrt3 + sqrt(3 + sqrt5))和(sqrt3 + sqrt(3-sqrt5))那么答案将会改变。
你如何解决arcsin(x)+ arcsin(2x)= pi / 3?
X = sqrt(( - 7 + sqrt(73))/ 16)arcsin(x)+ arcsin(2x)= pi / 3首先让alpha = arcsin(x)“”和“”beta = arcsin(2x)颜色(黑色)alpha和color(黑色)beta实际上只代表角度。所以我们有:alpha + beta = pi / 3 => sin(alpha)= x cos(alpha)= sqrt(1-sin ^ 2(alpha))= sqrt(1-x ^ 2)同样,sin(beta) )= 2x cos(beta)= sqrt(1-sin ^ 2(beta))= sqrt(1-(2x)^ 2)= sqrt(1-4x ^ 2)颜色(白色)接下来,考虑alpha + beta = pi / 3 => cos(alpha + beta)= cos(pi / 3)=> cos(alpha)cos(beta)-sin(alpha)sin(beta)= 1/2 => sqrt(1-x ^ 2 )* sqrt(1-4x ^ 2) - (x)*(2x)= 1/2 => sqrt(1-4x ^ 2-x ^ 2-4x ^ 4)= 2x ^ 2 + 1/2 => [sqrt(1-4x ^ 2-x ^ 2-4x ^ 4)] ^ 2 = [2x ^ 2 + 1/2] ^ 2 => 1-5x ^ 2-4x ^ 4 = 4x ^ 4
你如何简化(1 / sqrt(a-1)+ sqrt(a + 1))/(1 / sqrt(a + 1)-1 / sqrt(a-1))div sqrt(a + 1)/( (a-1)sqrt(a + 1) - (a + 1)sqrt(a-1)),a> 1?
巨大的数学格式......>颜色(蓝色)(((1 / sqrt(a-1)+ sqrt(a + 1))/(1 / sqrt(a + 1)-1 / sqrt(a-1)) )/(sqrt(a + 1)/((a-1)sqrt(a + 1) - (a + 1)sqrt(a-1)))=颜色(红色)(((1 / sqrt(a-) 1)+ sqrt(a + 1))/((sqrt(a-1)-sqrt(a + 1))/(sqrt(a + 1)cdot sqrt(a-1))))/(sqrt(a) +1)/(sqrt(a-1)cdot sqrt(a-1)cdot sqrt(a + 1)-sqrt(a + 1)cdot sqrt(a + 1)sqrt(a-1)))= color(蓝色)(((1 / sqrt(a-1)+ sqrt(a + 1))/((sqrt(a-1)-sqrt(a + 1))/(sqrt(a + 1)cdot sqrt(a -1))))/(sqrt(a + 1)/(sqrt(a + 1)cdot sqrt(a-1)(sqrt(a-1)-sqrt(a + 1)))=颜色(红色) ((1 / sqrt(a-1)+ sqrt(a + 1))/((sqrt(a-1)-sqrt(a + 1))/(sqrt(a + 1)cdot sqrt(a-1) ))xx(sqrt(a + 1)cdot sqrt(a-1)(sqrt(a-1)-sqrt(a + 1))