問題: 平面幾何 (平行四邊形+相似三角形)
Consider △CPB and △BPM, ∠CPM = ∠BPM = 90º (given) ∠PMB = 180º - ∠BPM - ∠PBM = 90º - ∠PBM ∠PBC = ∠MBC - ∠PMB = 90º - ∠PBM ∴, ∠PMB = ∠PBC Therefore, △CPB ∼ △BPM (A.A.A. ∼). Now, consider △CPD and △BPN, ∠DCP = ∠DCB - ∠P...
問題: 指數定律+科學記數法
今日喺Facebook見到有人問咗一條看似簡單, 但係又唔可以就咁用計數機㩒個答案出嚟嘅數。想喺依度同大家分享一吓:(begin{align}&dfrac{84^{90}-64^{80}}{20^{70}} \&= dfrac{84^{90}}{20^{70}}-dfrac{64^{80}}{20^{70}} \&= (dfrac{84^{9}}{20^{7}})^{10}-(dfrac{64^{8}}{20^{7}})^{10} \&= (162668553.5...