Solution: As shown in the figure.
D is the midpoint of the line segment AC,
Gets the length of the advertisement segment.
AD = DC = 1/2 AC = 5×( 1/2)= 2.5cm
identical
E is the midpoint of line segment CB,
Get the length of the line segment.
BE = CE = 1/2 BC = 4×( 1/2)= 2cm
∴ the length of line segment DE
DE=AB-AD-BE=9-2.5-2=4.5cm
Angle AOD and angle BOC are right angles. Given angle DOC=62, find the degree of angle AOB!
Solution:
There are two situations.
The first situation is as shown above.
∠∠BOD =∠BOC-∠DOC = 90-62 = 28，
∴? Angle AOB = ∠ AOD-∠ BOD = 90-28 = 62;
The second kind? The following figure
∠∠AOD+∠DOC+∠COB+∠AOB = 360，
Namely 90+62+90+∠ AOB = 360.
242 +∠AOB=360
∴? Angle AOB = 360-242 = 1 18.