Let $z = - 3 + 2 i$. Then in the complex plane, the point corresponding to $\bar { z }$ is located in A. the first quadrant B. the second quadrant C. the third quadrant D. the fourth quadrant
Given $\overrightarrow { A B } = ( 2,3 ) , \overrightarrow { A C } = ( 3 , t ) , | \overrightarrow { B C } | = 1$, then $\overrightarrow { A B } \cdot \overrightarrow { B C } =$ A． - 3 B． - 2 C． 2 D． 3
A speech competition has 9 judges who each give an original score for a contestant. When determining the contestant's final score, the highest and lowest scores are removed from the 9 original scores, leaving 7 valid scores. Compared with the 9 original scores, the numerical characteristic that remains unchanged for the 7 valid scores is A. median B. mean C. variance D. range
Let $\alpha , \beta$ be two planes. Then a necessary and sufficient condition for $\alpha \parallel \beta$ is A. There are infinitely many lines in $\alpha$ that are parallel to $\beta$ B. There are two intersecting lines in $\alpha$ that are parallel to $\beta$ C. $\alpha$ and $\beta$ are both parallel to the same line D. $\alpha$ and $\beta$ are both perpendicular to the same plane
If the focus of the parabola $y ^ { 2 } = 2 p x \ ( p > 0 )$ is a focus of the ellipse $\frac { x ^ { 2 } } { 3 p } + \frac { y ^ { 2 } } { p } = 1$, then $p =$ A． 2 B． 3 C． 4 D． 8
Among the following functions, which one has period $\frac { \pi } { 2 }$ and is monotonically increasing on the interval $\left( \frac { \pi } { 4 } , \frac { \pi } { 2 } \right)$? A．$f ( x ) = | \cos 2 x |$ B．$f ( x ) = | \sin 2 x |$ C．$f ( x ) = \cos | x |$ D．$f ( x ) = \sin | x |$