![](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>)
An organic substance A is composed of C, h and O. under certain conditions, the transformation relationship between a, B, C, D and E is as follows: It is known that the vapor density of C is 22 times that of hydrogen under the same conditions, and silver mirror reaction can occur (1) The name of the functional group contained in substance D is __, The structural formula of substance e is ___, (2) Write the chemical equation to achieve the following conversion: ①A→B______， ②A+O 2 →C______ ③ C equation for reaction with silver ammonia solution ___
(I) since sin (C-A) = 1, C − a =
π
two
, and C + a = π - B,
∴A＝
π
four
−
B
two
，
∴sinA＝sin(
π
four
−
B
two
)＝
two
two
(cos
B
two
−sin
B
two
)，
∴sin2A＝
one
two
(1−sinB)＝
one
three
，
And Sina > 0, ‡ Sina =
three
three
(II) as shown in the figure, it is obtained from the sine theorem
AC
sinB
＝
BC
sinA
∴BC＝
ACsinA
sinB
＝
six
•
three
three
one
three
＝3
two
，
Sinc = sin (a + b) = sinacosb + cosasinb=
three
three
×
two
two
three
+
six
three
×
one
three
＝
six
three
∴S△ABC＝
one
two
AC•BC•sinC＝
one
two
×
six
× three
two
×
six
three
＝3
two
An organic substance A is composed of C, h and O. under certain conditions, the transformation relationship between a, B, C, D and E is as follows: It is known that the vapor density of C is 22 times that of hydrogen under the same conditions, and silver mirror reaction can occur (1) The name of the functional group contained in substance D is __, The structural formula of substance e is ___, (2) Write the chemical equation to achieve the following conversion: ①A→B______， ②A+O 2 →C______ ③ C equation for reaction with silver ammonia solution ___
(I) since sin (C-A) = 1, C − a =
π
two
, and C + a = π - B,
∴A＝
π
four
−
B
two
，
∴sinA＝sin(
π
four
−
B
two
)＝
two
two
(cos
B
two
−sin
B
two
)，
∴sin2A＝
one
two
(1−sinB)＝
one
three
，
And Sina > 0, ‡ Sina =
three
three
(II) as shown in the figure, it is obtained from the sine theorem
AC
sinB
＝
BC
sinA
∴BC＝
ACsinA
sinB
＝
six
•
three
three
one
three
＝3
two
，
Sinc = sin (a + b) = sinacosb + cosasinb=
three
three
×
two
two
three
+
six
three
×
one
three
＝
six
three
∴S△ABC＝
one
two
AC•BC•sinC＝
one
two
×
six
× three
two
×
six
three
＝3
two
An organic substance A is composed of C, h and O. under certain conditions, the transformation relationship between a, B, C, D and E is as follows: It is known that the vapor density of C is 22 times that of hydrogen under the same conditions, and silver mirror reaction can occur (1) The name of the functional group contained in substance D is __, The structural formula of substance e is ___, (2) Write the chemical equation to achieve the following conversion: ①A→B______， ②A+O 2 →C______ ③ C equation for reaction with silver ammonia solution ___
(I) because sin (C-A) = 1, C − a = π 2, and C + a = π - B, ‡ a = π 4 − B2, ‡ Sina = sin (π 4 − B2) = 22 (cosb2 − sinb2), ‡ sin2a = 12 (1 − SINB) = 13, and Sina > 0, ‡ Sina = 33 (II) as shown in the figure, acsinb = bcsina ‡ BC = a
If ABC area of obtuse triangle is 1 / 2, ab = 1, BC = root 2, then what is AC
1/2=（1/2）AB*BC*sinB
I.e. 1 / 2 = (1 / 2) 1 * √ 2 * SINB
SINB = √ 2 / 2
So B = 45 or B = 135
When B = 45
AC ²= AB ²+ BC ²- 2AB*BC*cosB
=1+2-2√2*√2/2
=1
The triangle is a right triangle
So B = 135
Then AC ²= AB ²+ BC ²- 2AB*BC*cosB
=1+2+2√2*√2/2
=5
Get AC = √ 5
a. B and C are the three sides of triangle ABC, whose area is 12, radical 3, BC = 48, B-C = 2. Find a
From the triangular area formula s = (1 / 2) bcsina, then 12 √ 3 = (1 / 2) 48sina, that is, Sina = √ 3 / 2, from the triangular area formula s = (1 / 2) bcsina, then 12 √ 3 = (1 / 2) 48sina, that is, Sina = √ 3 / 2A = 60 ° or 120 °, BC = 48, B-C = 2, B = 8, C = 6, when a = 60 °, from the cosine theorem a = √ B ²+ c ²- 2bcc...
In the known triangle ABC, ab = root 3, AC = 1, and the area of triangle ABC = root 3 / 4. What is the length of BC?
Area of triangle = 0.5 * AB * ac * Sina
sinA=1/4
Cosa can be obtained
Then BC can be obtained by cosine theorem
RELATED INFORMATIONS
- 1. In triangle ABC, if a satisfies the root sign 3sina + cosa = 1, ab = 2, BC = 2 and root sign 3, the area of triangle ABC is
- 2. In triangle ABC, given sin (a + b) = 0.6, sin (a-b) = 0.2 and ab = 3, find the area of triangle ABC
- 3. In triangle ABC, cosa = 3 / 5, find the value of COS ^ (A / 2) - sin (B + C)
- 4. : if the area of triangle ABC is s and the three sides are a, B and C, what is the radius of the inscribed circle of the triangle?, : fill in the blanks, : it's probably expressed by a, B, C and s,
- 5. In △ ABC, a, B and C are the opposite sides of ∠ a, ∠ B and ∠ C respectively. If a, B and C form an equal difference sequence, ∠ B = 30 °, the area of △ ABC is 3 2, then B equals () A. 1+ three two B. 1+ three C. 2+ three two D. 2+ three
- 6. In triangle ABC, A.B.C is the length of the side opposite angle A.B.C, and S is the area of triangle ABC Know s = a Λ 2 - (B-C) Λ2. Find Tana
- 7. In triangular ABC, the ratio of angle a to angle B to the degree of angle c is 1 to 2 to 3 BC = 4. Calculate the area of triangular ABC
- 8. If triangle ABC is all equal to triangle a'b'c ', ab = 24 and triangle a'b'c' area = 180, then the height on the side of AB in triangle ABC is equal to?
- 9. As shown in the figure, in triangle ABC, ab = AC = 20, angle B is equal to 15 degrees, then the area of triangle ABC
- 10. In △ ABC, the opposite sides of angles a, B and C are a, B and C respectively, and meet 2C − B a＝cosB cosA． (I) find the size of angle a; (II) if a = 2 5. Find the maximum value of △ ABC area
- 11. In triangle ABC, the side length of the inner angle ABC is ABC respectively. It is known that C = 2 and C = 60 degrees. If SINB = 2sina, if the area of triangle ABC is equal to root 3
- 12. It is known that the coordinates of each vertex of triangle ABC are a (- 1,3) B (- 2, - 1) C (2,0) respectively. Find the area of triangle?
- 13. If the coordinates of the three vertices of a triangle are a (- - 5,2), B (1,2), C (3, - 10), then the area of triangle ABC
- 14. The object with mass m slides to the trolley with mass m originally stationary on the horizontal smooth plane at the horizontal initial speed V0, and the dynamic friction between the object and the trolley surface is μ, The trolley is long enough to calculate the displacement of the trolley from the time when the object slides onto the trolley to the time when it is relatively stationary with the trolley
- 15. As shown in the figure, a flat car with mass m moves in a straight line at speed V on a smooth horizontal plane. Today, an object with mass m is gently placed at the front end of the car. When the object is placed on the car, the horizontal speed relative to the ground is zero. Let the dynamic friction coefficient between the object and the car be μ， In order to prevent objects from sliding down from the trolley, the minimum length of the trolley is __
- 16. What is the purpose of a bicycle to increase friction and what is to reduce friction What parts?
- 17. In RT triangle ABC, angle c = 90 degrees, the opposite sides of angle a, angle B and angle c are a, B and C respectively. Let the area of triangle ABC be s and the perimeter be L Then S / L = (a + B-C) / 4, explain the reason for this conclusion
- 18. In △ ABC, a, B and C are the opposite sides of a, B and C respectively, and the area s = a2 - (B-C) 2, then Sina = () A. 15 seventeen B. 13 fifteen C. 8 seventeen D. 13 seventeen
- 19. In triangle ABC, a, B and C are the opposite sides of angle a, angle B and angle C respectively. If 2B = a + C, angle B = 30 °, the area of triangle ABC is 1 / 2, then B is?
- 20. In triangle ABC, angle c is equal to 90 degrees, angle a is equal to 15 degrees, and BC is equal to 4. Find the area of triangle ABC The figure is a single triangle