Question

已知角A与角B互余,且角A比角B小25度,求2角A-五分之一角B的值

Answer 1

已知角A与角B互余,则∠A+∠B=90°①

且角A比角B小25度,则∠B-∠A=25°②

由②得∠B=25°+∠A,

把∠B=25°+∠A代入①得∠A+25°+∠A=90°,

解得∠A=32.5°

则∠B=25°+∠A=25°+32.5°=57.5°

∴2∠A-(1/5)∠B=2×32.5°-(1/5)×57.5°

=65°-11.5°

=53.5°