how do you graph the equation y=-2cosx?
By drawing a rectangular coordinate system, the axes labelled x and y respectively. Proceed further by make a table in which you calculate the value of y for given x. Use these values to draw the graph in the coordinate system, the x-value being the abscissa and the y-value the ordinate.
When drawing use the approximation pi = 3.
I do not recommend using a pi = 3 approximation. You will end up with large y errors for |x|>10 . You can make the plotting easier if you choose x table entries and graph x-axis divisions that are multiples of pi/6 (30 degrees).
Would also be a possibility, however, it does depend on the scale, as you surely know. If we set pi ^= 3, it is clear what is meant and the recipient can easily calculate how the function looks like in real.
Use Pi = 3 ???
reminds me of the alleged Indiana State Legislature bill which attempted to make it law that pi be a rational number.
http://www.cs.uwaterloo.ca/~alopez-o/math-faq/mathtext/node18.html
I also recommend drwls' method, of using a unit grid value to represent pi/6 or even pi/12 (15 degrees)
The pi/12 division gives us exact positions for the most popular angles such as pi/4 (45 degrees) etc.
To graph the equation y = -2cos(x), you can follow these steps:
Step 1: Determine the range of x-values you want to plot. A common range is -2π to 2π, which covers one full cycle of the cosine function.
Step 2: Create a table of values by choosing various x-values within your chosen range. For example, you can choose x-values like -2π, -3π/2, -π, -π/2, 0, π/2, π, 3π/2, and 2π.
Step 3: Plug each x-value into the equation y = -2cos(x) to find the corresponding y-value. Use a calculator to evaluate the cosine function for each x-value. For example, if x = π/2, the corresponding y-value is -2cos(π/2) = -2(0) = 0.
Step 4: Once you have a set of points (x, y), plot them on a coordinate plane.
Step 5: Connect the points with a smooth curve. Since we are dealing with a cosine function, the graph will have a wave-like shape. It will oscillate between its maximum value (y = 2) and minimum value (y = -2) as x ranges from -2π to 2π.
Step 6: Label the x-axis with the chosen x-values and the y-axis with the corresponding y-values.
Your graph should resemble a wave, starting from the origin and then oscillating up and down. Remember, cosine has a maximum value of 1 at x = 0 and x = 2π, and a minimum value of -1 at x = -π and x = π. In this case, the -2 in front of cos(x) reflects and stretches the graph vertically by a factor of 2, so the maximum value becomes 2 and the minimum value becomes -2.