Question

19．已知∠A和∠B互余，∠A比∠B大10°，設(shè)∠A、∠B的度數(shù)分別為x°、y°，下列方程組在符合題意的是（　�。�

• A． $\left\{\begin{array}{l}{x+y=90}\\{x=y+10}\end{array}\right.$
• B． $\left\{\begin{array}{l}{x+y=90}\\{x=y-10}\end{array}\right.$
• C． $\left\{\begin{array}{l}{x+y=180}\\{x=y-10}\end{array}\right.$
• D． $\left\{\begin{array}{l}{x+y=180}\\{x=y+10}\end{array}\right.$

Answer 1

分析 根據(jù)題意可得等量關(guān)系：①∠A+∠B=90°；②∠A=∠B+10°，根據(jù)等量關(guān)系列出方程組即可．

解答 解：設(shè)∠A、∠B的度數(shù)分別為x°、y°，則
$\left\{\begin{array}{l}{x+y=90}\\{x-y=10}\end{array}\right.$，
即$\left\{\begin{array}{l}{x+y=90}\\{x=y+10}\end{array}\right.$，
故選：A．

點(diǎn)評(píng) 此題主要考查了由實(shí)際問題抽象出二元一次方程，關(guān)鍵是正確理解題意，找出題目中的等量關(guān)系，列出方程組．