A.材質(zhì) B.料厚 C.圖號(hào) D.爐號(hào)
A.πR2θ/360 B.πR2θ/180 C.πR2θ D.πR2θ/2
A.πR2α/360 B.πR2α/180 C.πR2α D.πR2α/2