2. In ABC, ∠ c = 90, DE is the intersection of the median vertical lines of AB and BC is D, the vertical foot is E, ∠BAD:∠CAB= 1:3, and the degree of ∠B is found.
3.BD bisects ∠ ABC, DE ⊥ AB, DF ⊥ BC, and E.F is the vertical foot, connecting EF. (1) Is there an isosceles triangle in the diagram? If so, write it out and be reasonable. (2) 2) Is BD perpendicular to EF? Why?
At 2 o'clock, 15 minutes, the angle between the hour hand and the minute hand is ().
⒒ 18 43′26〃=
5] 180 ÷ 7 (accurate to') =
⒔: It takes six minutes for the wheel to make three turns, so the angle at which the wheel rolls per second is ().
From 3: 45 pm to 8: 00 pm 2 1, the hour hand of the clock turned () degrees.
6. From 2: 00, 15 to 2: 30, the minute hand rotation angle of the clock is ().
When the clock is on the hour, the angle between the hour hand and the minute hand will be equal within 5 degrees. Please write down their degrees separately.
4. Given that one side of an isosceles triangle is 5 and the other side is 6, its circumference is
5. In △ABC, AB=AC, ∠A=3∠B, then ∠A= ∠C=
6. As shown in the figure (1), where ∠C=90 in △ABC? 0? 2，∠B=30？ 0? 2, CD is the height on the side of AB, E is a point on AB, and CE=BE.
(1) Write all isosceles triangles in the diagram.
(2) Write all equilateral triangles in the diagram.
(3) If DE=2cm, AB= cm and AC= cm.
7. It is known that the circumference of isosceles △ABC is 24cm, and the difference between the bottom edge and the waist length is 3cm.
So the base of this triangle is
8. If the outer angle of an isosceles triangle is 100? 0? 2, then its three internal angles are
9. One side of an isosceles triangle is 6, and the outer angle is 120? 0? 2, so its circumference is
10. As shown in Figure (2), let AB = AC, AD = BD = BC, and the three internal angles of △ABC are
1 1. The vertex angle of an isosceles triangle is 70? 0? 2, the angle between height and waist bottom is
12. The included angle between the height of one waist and the height of the other waist of an isosceles triangle is 35? 0? 2, then the base angle of this isosceles triangle is
13. The circumference of an isosceles triangle is, if the midline of a waist divides the circumference into 5: 3, the length of the bottom of the triangle is. The ratio of two angles of an isosceles triangle is 4: 1, and the top angle is.
∠p=25？ 0? 2, and PA=AB=BC=CD, then the degree of ∠CDE is, and the degree of ∠DCF is.
14. As shown in Figure (2), in △ABC, AB=AC, AD⊥BC is in D, the circumference of △ABC is 50 cm, AB+BD=AD=40 cm, then AD=
15. As shown in Figure (3)△ABC, AB=AC, EB=BD=DC=CF, ∠A=40? 0? 2, then EDF =
16. As shown in Figure (4)△ABC, AB=AC, AD=BD, AC=CD, then ∠B=
17 ... The midline of the waist of an isosceles triangle divides the circumference into 15 and 12, so its base length is
18. The circumference of an isosceles triangle is 26 cm. If a waist is used as an equilateral triangle with a circumference of 30 cm, the length of the base of the isosceles triangle is