Sudut BPC 50 derajat,sudut BRC 60 derajat,dan sudut BCR 70 derajat.hitunglah sudut sudut dalam segitiga ABC

Diketahui
<BPC = 50°
<BRC = 60°
<BCR = 70°

Ditanya
<ABC =...?

Jawab
<CBR =180° - (<BRC + <BCR) = 180°-(60°+70°)=180°-130° = 50°
<BCR = <PRQ = 60°
<BRP = 180°- <PQR = 180°-60° = 120°
<PBR = 180° - (<BRP+<BPR) = 180° - (120°+50°) = 180° - 170° = 10°
<ABC = <PBR + <CBR = 10° + 50° = 60°
<APC = 180° - <BPC = 180° - 50 ° = 130°
<QCR = <PBR = 10°
<CQR = <BPR = 50° 
<AQB = <APC = 130°
<BCQ = <BCA = <BCR + <QCR = 70° + 10° = 80°
<BAC = 180° - (<BCA+<CBA) = 180° - (80°+60°) = 180° - 140° = 40°