![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
In the inner △ ABC of ⊙ o, if OD ⊥ BC is at point D, ∠ BOD = 36 °, then the degree of ⊙ A is
In the inner △ ABC of ⊙ o, OD ⊥ BC is at point D, ∠ BOD = 36 °
Then ∠ cod = 36 ° so ∠ cob = 72 °,
So the degree of ∠ a = 36 degrees
Triangle ABC and triangle COD are isosceles triangle, angle AOB = angle cod = 90 degrees, D on AB, prove that triangle AOC is equal to triangle BOD
It should be: Triangle ABO and triangle COD are isosceles triangle, angle AOB = angle cod = 90 degrees, so OC = OD, OA = ob
Therefore, AOC = BOD so △ AOC ≌ BOD
As shown in the figure, in △ BOD, OB = 7, OD = 3, rotate △ BOD 90 ° counterclockwise around point O to the position of △ AOC, and calculate the area of the shadow part in the figure
∵△ AOC ≌△ BOD, ≌ the area of shadow part = the area of sector OAB - the area of sector OCD = 90 π × 72360-90 π × 32360 = 10 π
As shown in the figure, in △ BOD, OB = 7, OD = 3, rotate △ BOD 90 ° counterclockwise around point O to the position of △ AOC, and calculate the area of the shadow part in the figure
∵△ AOC ≌△ BOD, ≌ the area of shadow part = the area of sector OAB - the area of sector OCD = 90 π × 72360-90 π × 32360 = 10 π
RELATED INFORMATIONS
- 1. As shown in the figure, ⊙ o is the circumscribed circle of △ ABC, the chord CD bisects ∠ ACB, ∠ ACB = 90 ° to verify: Ca + CB = 2CD
- 2. As shown in the figure, the circle O is the circumscribed circle of △ ABC, the radius of circle O is 2, SINB = three quarters, then the length of chord AC is
- 3. It is known that AB is the diameter of circle O, the chord center distance of chord BC is 4, then the length of AC is? Do me a favor
- 4. In the triangle ABC, ab = AC, angle BCA = 80 degrees, O is a point in the triangle ABC, and the angle OBC = 10 degrees, angle oca-20 degrees
- 5. In the triangle ABC, ab = AC, BAC = 80 degrees, O is a point in the triangle ABC, OBC = 10 degrees, OCA = 20 degrees The picture shows
- 6. In the triangle ABC, there is a point O, OA = 3cm, OB = 4cm, OC = 5cm, find (1) ∠ AOB, ∠ AOC degree (2) find the respective area of triangle AOB, AOC, BOC emergency
- 7. In △ ABC, the bisectors of ∠ B and ∠ C intersect at point O. it is proved that ∠ BOC = a + ABO + ACO In △ ABC, the bisectors of ∠ B and ∠ C intersect at point O. it is proved that ∠ BOC = a + ABO + ACO All we need is the process, you know, complete@
- 8. In the triangle ABC, the degree of angle a is 100 degrees. If the bisector of angle B and angle c intersects point O, then the angle BOC and so on are equal to? choice question A. 100 degrees B. 140 degrees C. 60 degrees D. None of the above answers is correct
- 9. In △ ABC, ab = AC, the circle O with ab as diameter intersects BC at point D and AC at point e. it is proved that arc BD = arc De
- 10. 1. In triangle ABC, if a = 2, B = root 2, angle a = tt / 4, then angle B is equal to 2. In triangle ABC, if a = root 7, B = 3, C = 2, then angle a is equal to 2 The first and second questions have been solved
- 11. Given the isosceles triangle ABC, the base BC = 20, D is a point on AB, and CD = 16, BD = 12, find the length of AD
- 12. As shown in the figure, in triangle ABC, ∠ ACB = 60 ° AC ＞ BC, there are triangle ABC ', triangle BCA', triangle cab ' Better be more detailed
- 13. In the triangle ABC, D is the midpoint of the BC side, and it is proved that AD & # 178; = 1 / 2 (AB & # 178; + AC & # 178;) - 1 / 4 (BC & # 178;) It's all vectors
- 14. In the known triangle ABC, ad is the middle line. Prove AD & # 178; = (1 / 2) (AB & # 178; + AC & # 178;) - (BC / 2) &# 178;
- 15. BD is the bisector of angle ABC, De is perpendicular to AB and E, DF is perpendicular to BC and F, area of triangle ABC = 36, ab = 18, BC = 12, find the length of De and DF
- 16. In △ ABC, ab = 5cm, BC = 7cm, AC = 8cm. Draw three circles with a, B, C as the center respectively, and make them circumscribed, then the radius of ⊙ A is cm, In △ ABC, ab = 5cm, BC = 7cm, AC = 8cm. Draw three circles with a, B, C as the center, and make them two outside Then the radius of ⊙ A is cm, the radius of ⊙ B is cm, and the radius of ⊙ C is cm
- 17. In the triangle ABC, ab = 5, BC = 8 and AC = 7. Take a, B and C as the center respectively. Draw three circles and make them circumscribe each other. Find the radius of circle a, circle B and circle C
- 18. It is known that the lengths of three sides of a triangle are 4cm, 5cm and 6cm respectively. The three circles centered on each vertex are tangent to each other, and the radii of the three circles are calculated most urgent
- 19. As shown in the figure, △ ABC is inscribed on the circle O, ab = AC, cos ∠ ABC = four fifths. If the radius of circle O is 5cm, calculate the area of △ ABC (2) If BD bisector angle ABC, ah ⊥ CD is in H, find HC: BD
- 20. If AB = 3cm, AC = 4cm, ad = 2.5cm, find the radius of circle o