sin²θ+sinθcosθ+cos²θ
=(sin²θ+sinθcosθ+cos²θ)/1
=(sin²θ+sinθcosθ+cos²θ)/(sin²θ+cos²θ)分子分母同时除以cos²θ
=(sin²θ/cos²θ+sinθcosθ/cos²θ+cos²θ/cos²θ)/(sin²θ/cos²θ+cos²θ/cos²θ)
=[(sinθ/cosθ)²+sinθ/cosθ+1]/[(sinθ/cosθ)²+1]
=[tan²θ+tanθ+1]/[tan²θ+1]
=(2²+2+1)/(2²+1)
=(4+3)/(4+1)
=7/5这个问题的答案，我采纳你的！刚才的问题，你的答案我就不采纳了！还望理解！没关系