Does the angle between X, y, z axes in the coordinate system established by space vector have to be 90 degrees

No, draw according to different questions and actual situation

RELATED INFORMATIONS

1. It is known that: as shown in the figure, in RT △ ABC, ∠ C = 90 °, BC = 4, AC = 8, the point D is on the hypotenuse AB, make de ⊥ AC, DF ⊥ BC respectively, the perpendicular feet are e, f respectively, and get the quadrilateral decf, let de = x, DF = y. (1) use the algebraic formula containing y to express AE, and get AE=______ (2) find out the function relation between Y and X, and find out the value range of X; (3) let the area of quadrilateral decf be s, find out the maximum value of S
2. If the positions of rational numbers a, B and C on the number axis are shown in the figure below, where 0 is the origin. (1) find the value of the formula A / | a | + | B | / B + C / | C | + | ABC | / ABC --。 ---------------。 ----。 ---------。 ------------- a b 0 d
3. A motor, rated voltage is 220 V, rated power is 4 kW, ask: (1) 1 kW. H of electric energy for the normal operation of the motor how long?
4. The resistance of an electric furnace is 48.4 Ω. How much work does the current do when it is connected to a 220 V circuit and energized for 5 minutes?
5. A control circuit of hair dryer is designed. The sine input voltage of hair dryer is 50 Hz and 220 v. two resistors and position switches are required in the control circuit to realize three positions of 250 W, 500 W and 1000 W respectively. The equivalent circuit of switch in three positions of high, medium and low is drawn, and the component parameters are given
6. What is the maximum allowable voltage and current of a 2000 ohm resistor with a rated power of quarter watt?
7. 1) 2) what is the function of resistance?
8. In parallel circuit, if one resistance decreases, what is the current shared by this resistance and what is the voltage, resistance and power of the other resistance in parallel In a series circuit, if one resistance decreases, what is the current shared by this resistance, and what is the voltage, resistance and power of the other resistance in series
9. In the series circuit of constant value resistor, sliding rheostat and ammeter, the voltmeter is connected in parallel at both ends of the resistor. If the voltage expression is 0 during the experiment, If the current indicator is 0 and the voltage indicator increases suddenly, what fault will happen?
10. Suppose that two resistors with resistance values of 1 ohm and 10 ohm are connected in parallel, and their equivalent resistance is R1. Three resistors with resistance values of 1 ohm, 10 ohm and 100 ohm are connected in parallel After (connecting), the equivalent is set to R2 A. R1 ＞ R2 B. R1 ＜ R2 C. R1 = R2 D. cannot be determined
11. If a set of data x1, X2 If the average of XN is 2 and the variance is 9, then the data are 2x1-3, 2x2-3 What are the average and variance of 2xn-3?
12. If the sequence {CN} = {an} * {BN}, {an} is the arithmetic sequence and {BN} is the proportional sequence Find the sum SN of {CN}
13. On the oscillation discontinuity of Higher Mathematics f（x）=sin（1/x）+1,x>0, sin（1/x）-1,x
14. What's the difference between arithmetic left shift, logic left shift, arithmetic right shift and logic right shift? Arithmetic left shift: add 0 at the end; logic left shift: add 0 at the end Arithmetic shift right: fill in the lowest bit at the left end; logic shift right: add 0 at the left end Why are there such differences? In addition, why are arithmetic left shift and logic left shift the same? In this case, why are there two kinds of instructions? Arithmetic shift right, is the left end of the highest fill
15. Solve the equation 2.8x4-5x = 5.8 Solving practical problems with equations Two engineering teams jointly build a 3.9 km long highway, which will be completed in 20 days. It is known that team a builds 0.1 km per day, and team B how many km per day? Xiaoqing and her mother went to the shopping mall to buy two boxes of chocolate, 59.8 yuan per box, and 4.5 kg of candy, 14.6 yuan per kg. How much did they spend?
16. A new two digit number is four seventh of the original number What is the original two digit number? How many such two digits are there?
17. M is a point on parallelogram ad. if the area of parallelogram ABCD is equal to 4 square centimeters, how many square centimeters is the area of triangle MBC equal to?
18. Trapezoid ABCD, M is the waist midpoint of AD, triangle ABM area is 8, triangle MCD is 12, calculate the area of triangle BMC
19. As shown in the figure, M is a point on the side ad of the parallelogram. If the area of the parallelogram ABCD is four square centimeters, what is the area of the triangle MBC
20. As shown in the figure, in trapezoidal ABCD, ad ∥ BC, diagonal AC and BD intersect vertically at O, Mn is the median line of trapezoidal ABCD, ∠ DBC = 30 °, verification: AC = Mn