赞
xin5570281 花朵
共回答了382个问题 举报
270° < θ/2 < 360° => 540° < θ < 720°
cos(θ/2) = √(1 + x)/x
对边 = -√[x² - (1 + x)] = -√(x² - x - 1)
sin(θ/2) = -√(x² - x - 1)/x，第四象限，负值
sinθ = 2sin(θ/2)cos(θ/2) = 2 * -√(x² - x - 1)/x * √(1 + x)/x
= -2√[(x + 1)(x² - x - 1)]/x²
cos(θ/2) = √(1 + x)/x
对边 = -√[x² - (1 + x)] = -√(x² - x - 1)
sin(θ/2) = -√(x² - x - 1)/x，第四象限，负值
sinθ = 2sin(θ/2)cos(θ/2) = 2 * -√(x² - x - 1)/x * √(1 + x)/x
= -2√[(x + 1)(x² - x - 1)]/x²
1年前
0
可能相似的问题