Respuesta :

check the picture below


for the DB length, make sure your calculator is in Degree mode, since the angles are in degrees.
Ver imagen jdoe0001
Ver imagen jdoe0001
mreijepatmat
a) mes ∠ DAB) = mes ARC DAB/2

if mes ARC DAB = 40° , then mes DAB = 20

b) ∠ BDA  is inscribed in half cercle, so its mesure is 90°

c) ∠DBA =90° - 20° = 70° (COMPLEMENTARY angles in a right triangle)

d) LENGTH OF ARC DB:

The central angle DCB = mes ARC DB = 40°;

 Arc LENGTH = (40°) * (2πR)/360°, with R = 12 and π ≈ 3.14

Arc Length = (40°)*2*3.14*12/360 = 8.37 CM