利用单位圆解三角问题 ,既形象又直观 ,简单易行 ,操作方便 ,本文介绍给同学们 .(注 :单位圆———半径为 1的圆 )图 1如图 1,∠MON =90° ,以O为圆心 ,1个单位长为半径作圆 ,交OM、ON于点A、B ,射线OP交⊙O于点C ,过点C作CD⊥ON于D ,过点B作BE⊥ON于B ,交OP于E点 ,过点A作AF⊥ The use of unit circle to solve the triangle problem is both visual and intuitive, simple and easy to operate. This article is introduced to the students. (Note: unit circle - circle with a radius of 1) Figure 1 As shown in Figure 1, ∠ MON = 90° , with O as the center of the circle, a unit with a radius of radius for the circle, OM, ON at points A, B, ray OP intersect with O at point C, point C for CD ⊥ ON at D, point B for BE ⊥ ON in B, hand over OP at point E, over point A for AF