-Sin30 ° multiplied by - cos60 ° =?

-Sin30 ° multiplied by - cos60 ° =?

-Sin30 ° multiplied by - cos60 '
=Sin 30 ° times cos 60
=1 / root 3 x 1 / root 3
=1 / 3
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Sin α + cos α = 1 / 3, Tan α + cot α

Square the two sides of the conditional expression, sin * cos = - 4 / 9
tan+cot=(sin^2+cos^2)/sin*cos=-9/4

To solve an equation with trigonometric function, please explain the solution (teach me how to solve it) I'm on the third day of junior high school. Please be more specific Take the following question as an example: sinC/8=Sin（3∠C）/10 Please make it clear If you come across sinC/8=Sin（∠C+45°）/10 What to do There is no difference

In order to solve sinc / 8 = sin (3 ∠ C) / 10, it is better to know the trigonometric formula sin (3C) = 3sinc-4sinc ^ 3, then sinc / 8 = (3sinc-4sinc ^ 3) / 10, so we have sinc = 0 or (3-4sinc) / 10 = 1 / 8, and find sinc = 7 / 16

How to solve inverse trigonometric function equation with MATLAB Equation: arctan (0.2 * W) + arctan (0.02 * W) = 90 degrees How can this equation get the value of W in MATLAB?

>> syms w
>> solve('arctan(0.2*w)+arctan(0.02*w)=pi/2 ')

Solution of inverse trigonometric function sin()=sin() cos()=cos() tan()=tan()

x,arcsinsinx
x,arcoscosx
x arctantanx

On the equation of inverse trigonometric function arcsin(20/29)=arccosx How to calculate the problem

Let Sina = 20 / 29, then cosa = √ [1 - (20 / 29) ^ 2] = 21 / 29
Therefore, arcsin (20 / 29) = arccos (21 / 29) = arccosx
=> x=2kπ(+/-)21/29 (k∈Z)

The solution set of √ 2Sin (2x - π / 3) - 1 = 0

| x = k Π + 7 / 24 Π or x = k Π + 13 / 24 Π, K ∈ Z}

How to find trigonometric function equation?

First calculate the solution of the simplest and most familiar trigonometric function, and then replace the independent variable
for instance:
sin(2x+π/6)≥√2/2
First, SiNx ≥ √ 2 / 2 is solved
The solution is 2K π + π / 4 ≤ x ≤ 2K π + 3 π / 4
Then the independent variable 2x + π / 6 of trigonometric function is replaced by X in the solution set
2kπ+π/4≤2x+π/6≤2kπ+3π/4
And then work out X

Trigonometric functions and equations The known function y = (SiNx + cosx) ^ 2 + 2 (cosx) ^ 2 (1) Find its increasing interval (2) Find its maximum and minimum Please write clearly how to simplify,

First, simplify: y=
Increasing range: (- 3 π / 8 + K π / 2, π / 8 + K π / 2)
Maximum: 2 + (√ 2)
Minimum: 2 - (√ 2)
The following formula is mainly used in simplification
1. Double angle: cos2x = 2 (cosx) ^ 2-1
2. Sum of squares formula: (SiNx) ^ 2 + (cosx) ^ 2 = 1
3. To the most important sin2x + cos2x, first extract (√ 2) and change it into
(√2)*((√2)/2*sin2x+(√2)/2*cos2x)=2+(√2)*sin(π/4+2x)
I'm sorry, there were some mistakes in my answer, which have been corrected now

Trigonometric function equation It is known that f (x) = asin (MX + n); X is in the focus of the X axis and the image (a > 0, M > 0, 0 < n < 90) on R. the distance between the two adjacent focuses is π / 2, and the image passes through the lowest point (2 π / 3, - 2) 1. Find f (x) 2. When x ∈ [π / 12, π / 2], find the range

1. If the distance between two adjacent focal points is π / 2, the period is π, that is 2 π / M = π, M = 2; if the image passes through the lowest point (2 π / 3, - 2), then a = - 2 ∣ = 2, f (x) = 2Sin (2x + n), because f (2 π / 3) = - 2, sin (4 π / 3 + n) = - 2, sin (4 π / 3 + n) = - 1,0 ＜ n ＜ π / 2, n = π / 6, then f (x) =