Question

如图,△ABC中,∠B=∠C,∠BAD=40°,且∠ADE=∠AED求∠CDE等于多少度

Answer 1

∵ ∠B＝∠C, ∠BAD=∠ADC-∠B ,

∴ ∠BAD=∠ADC-∠C ,

∴ ∠BAD=(∠ADE+∠CDE)-(∠AED-∠CDE ),

又∵ ∠ADE=∠AED ,

∴ ∠BAD=2∠CDE ,

∵ ∠BAD=40°,

∴ ∠CDE=20°.