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As shown in the figure, in the square grid, if the side length of each small square is 1, the number of sides with irrational side length in triangle ABC on the grid is () A. 0 B. 1 C. 2 D. 3
Observe the graph, apply Pythagorean theorem, get
AB=
42+12＝
17，
BC=
32+12=
10，
AC=
42+32=5，
Both sides of AB and BC are irrational numbers
Therefore, C
As shown in the figure, in a 4 × 4 square grid, the vertices a, B and C of △ ABC are on the vertex of the unit square. Please draw a △ a1b1c1 in the figure so that △ a1b1c1 ∷ ABC (similarity ratio is not 1), and points A1, B1, C1 are all on the vertex of the unit square______ .
As shown in the figure
(1) Let △ a ′ B ′ C ′ be symmetric with respect to the line Mn (2) If the side length of each small square in the grid is 1, find the area of △ ABC
(1) As shown in the figure:
(2) Area of △ ABC: 2 × 4-1
2×2×1-1
2×4×1-1
2×2×2=3．
Known: as shown in the figure, points a, B, C, D, e are all on the vertices of the small square in the grid composed of small squares with side length of 1. Calculate the value of Tan ∠ ADC
AC = BC=
5，CD=CE=
10, ad = be = 5, (3 points)
≌△ BCE. (4 points)
∴∠ADC=∠BEC．
∴tan∠ADC=tan∠BEC=1
3. (5 points)
Drawing method of triangle area to find the root number of side length root 10, root 29 and root 61 Using the Pythagorean theorem, Helen's formula does not work
The triangle area of side length root 10, root 29, root 61
=5*6/2-5*2/2-1*2-1*3/2
=9
As shown in the figure, the side length of each small square in the square grid is 1, and the vertex of each small grid is called a lattice point Draw triangles and parallelograms in the mesh according to the following requirements (1) Are the three sides of the triangle 4, 13 and 5 respectively
It mainly uses Pythagorean theorem
You can make 15 degrees and 22 degrees with a ruler and gauge. Use the figures you draw to find their sine, cosine and tangent function values
Let AC = 1, then BC = radical 3, ab = 2 & nbs
Find the sine, cosine and tangent functions of 390?
According to the periodicity formula of trigonometric function, the period of sine and cosine functions can be solved by sin390 ° = sin (360 ° + 30 °) = sin30 ° = 1 / 2cos390 ° = cos (360 ° + 30 °) = cos30 ° = √ 3 / 2 (the root of two thirds is three) tan390 ° = Tan (360 ° + 30 °) = tan30 ° = √ 3 / 3 (the root of three thirds is three)
Sine theorem formula c/b=sinc/sinb
Yeah
By the way, I'll give you a few more formulas about trigonometric functions
(1) Sum difference formula
* sin(α+β)=sinαcosβ+cosαsinβ
* cos(α+β)=cosαcosβ-sinαsinβ
* tan(α+β)=(tanα+tanβ)/1-tanαtanβ
(2) Formulas in triangles
* sin(A+B)=sinC
* cos(A+B)=-cosC
* tan(A+B)=-tanC
* tanA+tanB+tanC=tanAtanBtanC
* sin(A+B)/2=cosC/2
* cos(A+B)/2=sinC/2
* tan(A+B)/2=cotC/2
What is the formula of sine theorem? fast
Sine theorem
In a triangle, the ratio of each side to the sine of its opposite angle is equal
A / Sina = B / SINB = C / sinc = 2R (2R is a constant in the same triangle and is twice the radius of the circumscribed circle)
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