Question

Tolong yang bisa pake caranya ya..
Makasih

Answer 1

<ABC + <BCA + <CAB = 180°

<ADE + <DEC + <ECA + <CAD = 360°

<ADE + 115° + <ECA + 65° = 360°

<ADE + <ECA = 360 - 180 = 180°

<ADE = 180° - <ECA

<ADE + <EDB = 180°

180° - <ECA + <EDB = 180°

<ECA = <EDB

<BED + <DEC = 180°

<BED + 115° = 180°

<BED = 65°

<EDB + <DBE + <BED = 180°

<ECA + <DBE + 65° = 180°

<ECA + <DBE = 180-65 = 115°

<CAB + <ABC + <BCA = 180°

65° + <ABC + <BCA = 180°

<ABC + <BCA = 115°

<ECA = <BCA

<ECA = 115° - <ABC

karena ketiga sudutnya bersesuaian, maka ∆ABC dan ∆DEB sebangun dengan titik A =E dan C = D

maka DE/AC = BE/AB

8/10 = BE/ 20

BE = 20 x 8/10 = 16 cm (B)