1. Line segment AB=5, extend AB to C, make BC = 2ab, and D is the midpoint of AB, and find the length of DC.

Solution: According to the meaning, DB= 1/2AB=2.5.

because

BC=2AB (known)

therefore

BC= 10 (equivalent substitution)

because

DC=DB+BC

therefore

DC= 12.5 (properties of the equation)

2. In the Rt triangle ABC, two acute bisectors AO and BO intersect at point O, and the degree of angle AOB is found.

Solution: Angle A+ Angle B = 90

Angle OAB+ Angle Oba = (Angle A+ Angle B)/2=45.

Angle AOB= 180- Angle OAB- Angle OBA= 135.

3. In triangle ABC, the bisector of angle A and angle B intersect at point O, and when angle C is equal to several degrees, angle AOB=3. Angle c?

Solution: Angle A+ Angle B = 90

Angle OAB+ Angle Oba = (Angle A+ Angle B)/2=45.

Angle AOB= 180- Angle OAB- Angle OBA= 135.