(cos40°+sin50°(1+√3tan10°))÷(sin70°√(1+cos50°))
=(cos40°+sin50°(1+√3sin10°/cos10°))÷(sin70°√(2(cos25°)^2)
=(cos40°+sin50°(cos10°+√3sin10°)/cos10°)÷(√2sin70°cos25°)
=(cos40°+2sin50°sin40°/cos10°)÷(√2sin70°cos25°)
=(cos40°+2cos40°sin40°/cos10°)÷(√2cos20°cos25°)
=(cos40°+sin80°/cos10°)÷(√2cos20°cos25°)
=(cos40°+1)÷(√2cos20°cos25°)
=2(cos20°)^2÷(√2cos20°cos25°)
=√2cos20°/cos25°)
题目是不是有问题啊?