1/tansinsinc/sinC=2R
| b/a | a/c | b/c |
| y/x | x/r | y/r |
| 1+tan2Ɓ1/cos2 | sin2Ɓ{cos2ƁP | sin/cos |
| 0,1/3,1,3,Ȃ | 1,3/2,2/2,1/2,0 | 0,1/2,2/2,3/2,1 |
| -3,-1,-1/3,0 | -1/2,-2/2,-3/2,-1 | 3/2,2/2,1/2,0 |
| 1/tan |
sin |
cos |
| }tan | -cos | sin |
| cosAb2+c2-a2/2bc | a2=b2+c2-2bccosA | a/sinA=b/sinB= c/sinC=2R |
| S=(s-a)(s-b)(s-c)s | S=(a+b+c)r/2 | S=bcsinA/2 |