Sine, cosine, tangent and cotangent

9000038909

Level: 
B
Consider the function \(f\colon y =\sin \left (\frac{x} {2} + \frac{\pi } {2}\right )\). In the following list identify the function which has the same graph as the graph of the function \(f\).
\(g\colon y =\cos \frac{x} {2} \)
\(k\colon y =\cos \left (\frac{x} {2} + \frac{\pi } {2}\right )\)
\(b\colon y =\cos \left (\frac{x} {2} - \frac{\pi } {2}\right )\)
\(h\colon y =\cos \left (\frac{x} {2} -\pi \right )\)
\(m\colon y =\cos 2x\)

9000038910

Level: 
B
Consider the function \(f\colon y =\mathop{\mathrm{cotg}}\nolimits x\). In the following list identify the function which has the same graph as the graph of the function \(f\).
\(k\colon y = -\mathop{\mathrm{tg}}\nolimits \left (x + \frac{\pi } {2}\right )\)
\(g\colon y = -\mathop{\mathrm{tg}}\nolimits x\)
\(b\colon y =\mathop{\mathrm{tg}}\nolimits \left (x + \frac{\pi } {2}\right )\)
\(h\colon y =\mathop{\mathrm{tg}}\nolimits \left (x - \frac{\pi } {2}\right )\)
\(m\colon y = -\mathop{\mathrm{tg}}\nolimits x - \frac{\pi } {2}\)

1003076702

Level: 
C
The domain of the expression \( \frac{\cos⁡ x}{1-\sin ⁡x} \) is the set:
\( \left\{x\in\mathbb{R}\colon x\neq\frac{\pi}2 + 2k\pi\text{, } k\in\mathbb{Z} \right\} \)
\( \mathbb{R} \)
\( \left\{x\in\mathbb{R}\colon x\neq\frac{3\pi}2 + 2k\pi\text{, } k\in\mathbb{Z} \right\} \)
\( \left\{x\in\mathbb{R}\colon x =k\pi\text{, } k\in\mathbb{Z} \right\} \)