数学题cos²75°+cos²15°+4cos²75°·cos²15°的值等于
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![数学题cos²75°+cos²15°+4cos²75°·cos²15°的值等于](/uploads/image/z/7172457-33-7.jpg?t=%E6%95%B0%E5%AD%A6%E9%A2%98cos%26%23178%3B75%C2%B0%EF%BC%8Bcos%26%23178%3B15%C2%B0%EF%BC%8B4cos%26%23178%3B75%C2%B0%C2%B7cos%26%23178%3B15%C2%B0%E7%9A%84%E5%80%BC%E7%AD%89%E4%BA%8E)
数学题cos²75°+cos²15°+4cos²75°·cos²15°的值等于
数学题cos²75°+cos²15°+4cos²75°·cos²15°的值等于
数学题cos²75°+cos²15°+4cos²75°·cos²15°的值等于
cos²75°+cos²15°+4cos²75°·cos²15°
=cos²75°+sin²75°+4cos²75°*sin²75°
=1+(2cos75°*sin75°)²
=1+(sin150°)²
=1+sin²30°
=5/4
5/4