如图,CA=CD,∠B=∠E,∠BCE=∠ACD.求证:AB=DE.
计算: - ( - 4 ) + | - 5 | + 1 2 - 3 0 - 4 tan 45 ∘ .
计算: 3 25 + ( - 2 ) 3 - ( π - 3 ) 0 .
解方程组: 3 x - y = 2 9 x + 8 y = 17 .
计算: 9 + 2 sin 60 ∘ + | 3 - 3 | - ( 2016 - π ) 0 .
解方程组 x + y = 5 2 x + y = 11 .