High school math trigonometry has answers that I can t understand

<> if there is a BA vertical CA, which contradicts question 1, so the answer is wrong, or the question is wrong.

This student, this question is a test of the image and properties of trigonometric functions, for 2sinx=2, sinx=1, x=2k + 2, k z, this is the property of the sinusoidal function, you need to understand and memorize, because the trigonometric function is a periodic function, so you need to add 2k, k must take an integer, and then take the value of k according to the requirements of the question, so as to get , in fact, this question is also very simple, after finding w, you can exclude c, d, and then bring the point (3, 2) into a, B two items can get the correct answer A, and the multiple-choice question is to use the most convenient solution to quickly answer and save time.

Epochal t 2 Peak point Trough point Vulture 3 (-Vulture 3) Vulture 2, t Vulture

The definition of angle is that the origin o is the vertex, the beginning edge is on the x-axis, rotates around the origin o, is negative clockwise, positive counterclockwise, the terminal edge falls on the first quadrant is the quadrant angle, and the terminal edge falls on the coordinate axis is the coordinate axis angle. This is an extension of the concept of horns. In this way, the angle is a set, for example, a 60 degrees, 360 degrees k 60 degrees is a 60 degrees, and a 4 is a 2k 4.

That's the answer to the first question.

From the diagramIt can be obtained: a=2, and the period is t=2[ 3-(-6)]=t=2 2,

y=2sin(2x+ ) from (3,2) we can know that when 2 3+ =2 y=2, 6, so choose: a

Add 2k because the trigonometric function is a periodic function that is repeated at each point by the value of the 2k function: e.g. y=2 when x=3, x=2k + 3, y=2 (k is an integer).

Think of the formula with independent variables in parentheses as a whole t, 2sint=2, sint=1, and t=2 3+ because the sine function is a periodic function, add a k.

Since the point (3,2) is the highest point of the function image, the corresponding angle 2 3+ = 2+2k, and 2k is to facilitate the selection of the value to find the corresponding selection branch.

Because there's not just one solution.

Special Topics in Senior Secondary Mathematics: Trigonometric Function Problems Question Type 1 Problems related to the image and properties of trigonometric functions Example 1 (12 marks) Known functions f(x) cos x·sin x

3cos2x

34,x∈r.(1) Find the minimum positive period of f(x); (2) Find f(x) in the closed interval

Maximum and minimum values on 4. Normative solution Solution (1) From the known f(x) cos x·

12sin x

3 2cos

x－3cos2x

Because sin +cos = 1 5, the square sin cos on both sides 2sin cos = 1 25, and the stool is called sin cos 1, so 1+2sin cos = 1 25, 2sin cos = 24 25

So (sin -cos) sin cos 2sin cos = 1 - (-24 25) = 49 25, because - 2< <0, so sin <0, cos > 0, sin -cos < 0, so sin -cos = 7 5, simultaneous sin + cos = 1 5, solution sin = 3 5, cos = 4 5, so tan a = sin cos = 3 4

If the left equation is replaced by 1 generation after the pure neutral square of the left equation, there are 2 values of tan to solve, and sin and cos are still required to determine.

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In this problem, we first judge the range of +4 based on the fact that the sine value of +4 is the sum of the fourth quadrant, and then we get the range of - 4 based on the range of +4.

Then, according to the trigonometric identity transformation, the sine of +4 is converted into the cosine of the angle -4, and finally the value of sin( - 4) is found according to sin ( 4) + cos ( 4)=1.

Then the value of tan( - 4) = sin( - 4) cos( - 4) is obtained according to tan( - 4).

Hope it helps!

sin( 4) 5 3 1, the question is problematic, sin should be less than 1.

Knowledge points: sinx is positive in the first and second quadrants, three or four is negative, cosx is positive in the first four quadrants, and two and three are negative.

sinx) 2+(cosx) 2=1, cos(-80°)=k>0 gives sin(-80°)=1-k2

tan(-80)=sin(-80°)/cos(-80°))1-k^2)/k =tan100°

Solution: Because: [cos(-80)] 2+[sin(-80)] 2=1 so: [sin(-80)] 2=1 -k 2 and because sin(-80) is negative.

So sin(-80)=-1-k2

tan(-80)=sin(-80)/cos(-80)=-1-k^2)/k

tan100=tan(-80)=-1-k^2)/k

The odd change of the mantra does not change, and the symbol looks at the odd and even in Quadrant K 2, and the change refers to sina cosa

cos100°=cos（180°-80°）=cos（-80°）=ksin100°=√1-k^2

tan100°=-1-k2) k sin(-80)=-1-k2a, and y is negative in the fourth quadrant.

into a single trigonometric function.

1）f（x）=-（cos²x-sin²x）-2√3sinxcosx=-cos2x-√3sin2x

2 [(1 2)cos2x dec (3 2) sin2x] = -2 [sin2xcos( 6) deca cos2xsin( 6)] = -2sin (2x ten 6).

It's simple.