1).2/3sin^2x+1/4cos^2x
=(2/3sin²x+1/4cos²x)/(sin²x+cos²x)这边同时除以sinxcosx
=(2/3tanx+1/4cotx)/(tanx+cotx)
=(4/3+1/8)/(2+1/2)
=7/12
2).2sin^2x-sinxcosx+cos^2x
=(2sin^2x-sinxcosx+cos^2x)/(sin²x+cos²x)同时除以sinxcosx
=(2tanx-1+cotx)/(tanx+cotx)
=(4-1+1/2)/(2+1/2)
=7/5 1).2/3sin^2x+1/4cos^2x
=(2/3sin²x+1/4cos²x)/(sin²x+cos²x)这边同时除以sinxcosx
=(2/3tanx+1/4cotx)/(tanx+cotx)
=(4/3+1/8)/(2+1/2)
=7/12
2).2sin^2x-sinxcosx+cos^2x
=(2sin^2x-sinxcosx+cos^2x)/(sin²x+cos²x)同时除以sinxcosx
=(2tanx-1+cotx)/(tanx+cotx)
=(4-1+1/2)/(2+1/2)
=7/5