Giải thích các bước giải:
Ta có:
`hatA=2hatB=2.50^0=100^0`
`=>hatA+hatB=100^0+50^0=150^0`
Mà `hatA+hatB+hatC+hatD=360^0`
`=>hatC+hatD+150^0=360^0`
`=>hatC+hatD=210^0`
Mà `hatC=2hatD`
`=>2hatD+hatD=210^0`
`=>3hatD=210^0`
`=>hatD=70^0`
`=>hatC=2.70^0=140^0.`
Vậy `hatA=100^0;hatB=50^0;hatC=140^0;hatD=70^0.`