Questions: Three graphs are given below.
For each, choose its equation from the following.
y=2 sec x y=sec (x+π/4) y=tan x
y=cot (x-π/4) y=-2+csc x y=-cot x
Equation:
(Choose one)
Equation:
(Choose one)
Equation:
(Choose one)
Transcript text: Three graphs are given below.
For each, choose its equation from the following.
\[
\begin{array}{lll}
y=2 \sec x & y=\sec \left(x+\frac{\pi}{4}\right) & y=\tan x \\
y=\cot \left(x-\frac{\pi}{4}\right) & y=-2+\csc x & y=-\cot x
\end{array}
\]
Equation:
(Choose one)
Equation:
(Choose one)
Equation:
(Choose one)
Solution
Solution Steps
Step 1: Analyze the first graph
The first graph resembles a secant or cosecant function. The graph has asymptotes at $x = \frac{\pi}{4}$ and $x = \frac{3\pi}{4}$, which is a period of $\pi/2$. The standard period of secant and cosecant is $2\pi$. Since $\frac{2\pi}{B} = \frac{\pi}{2}$, we have $B=4$. The graph has a minimum at $y=2$ and a maximum at $y=-2$, so the amplitude is 2. The graph appears to be $2 \sec 4x$.
Step 2: Analyze the second graph
The second graph resembles a secant or cosecant graph shifted vertically. The graph appears to be shifted down by 2 units. The asymptotes are at $0$ and $\pi$, so the period is $\pi$. Thus $B=2$. The graph resembles $-2 + \csc 2x$.
Step 3: Analyze the third graph
The third graph resembles a tangent or cotangent graph. The graph appears to be of cotangent since it is decreasing. The asymptotes are at $0$ and $\frac{\pi}{2}$, meaning the period is $\frac{\pi}{2}$. Thus $B=2$. The graph resembles $\cot 2x$. However, $\cot x$ goes to positive infinity as $x$ approaches 0 from the right, and the given graph goes to negative infinity as $x$ approaches 0 from the right. Thus, the graph is $-\cot 2x$.
Final Answer:
First graph: $y = 2\sec(4x)$
Second graph: $y = -2 + \csc(2x)$
Third graph: $y = -\cot(2x)$