(1) ∠x を求めなさい.
43° 43° x 39° |
(2) ∠x を求めなさい.
65° A 31° B 32° C x D E |
(3) ∠x を求めなさい.
80° A x B 30° C 140° D E F |
(4) ∠x を求めなさい.
80° A 30° B x C 136° D E F |
(1) ∠x を求めなさい.
43° 43° x 39° 対頂角 = 180−(∠x+43) = 180−(43+39) ∠x = 39 |
(2) ∠x を求めなさい.
65° A 31° B 32° C x D E ∠BEC = 65 + 31 = 96 ∠BDCは△DCEの頂点Dにおける外角だから∠BDC = ∠C+∠BEC ∠BDC = 32+96 = 128 |
(3) ∠x を求めなさい.
80° A x B 30° C 140° D E F ∠CFB = 80 + 30 = 110 ∠BDCは△BDFの頂点Dにおける外角だから∠BDC = ∠B+∠CFB ∠B = ∠x = ∠BDC − ∠CFB = 30 |
(4) ∠x を求めなさい.
80° A 30° B x C 136° D E F よって,∠DFB = ∠BDC − ∠B = 136 − 30 = 106 ∠DFBは△AFCの頂点Fにおける外角だから∠DFB = ∠A+∠C ∠DFB = ∠A + ∠x = 106 よって,∠x = 26 |