Answer:  Option B and option D.
Step-by-step explanation:
 We know that a quadrilateral is a 2-dimensional closed shape that has four sides.
 By definition the diagonals of a quadrilateral are the lines that connect two non-adjacent vertices.
 The following quadrilaterals have diagonals that are perpendicular to each other (also known as perpendicular bisector diagonals), which means that they form four angles of 90 degrees (right angles): <em>Rhombus and Square.</em>
 Therefore the answers are: the option B and the option D.
 
        
             
        
        
        
The "dot product" of two vectors has several different formulas.
Since you are given the x- and y-coordinates of both vectors a and b, we can apply the formula
a dot b  = ax*bx + ay*by, where ax=x-component of vector a, by=y comp of vector b, and so on.  
So, for the problem at hand, ax * bx + ay * by becomes
3(-2) + (-8)(-6) = -6 + 48 = 42 (answer).  Note that the dot product (or "scalar product" is itself a scalar.
        
             
        
        
        
Answer:
32
Step-by-step explanation:
I did the mathmathics
 
        
                    
             
        
        
        
Answer:
6
Step-by-step explanation:
80- 34.34 = 45.66
45.66 ÷ 7.61 = 6
 
        
                    
             
        
        
        
Answer:
The tree is 16.25 m tall. 
Step-by-step explanation:
Attached is a diagram that better explains the problem. 
From the diagram we see that the distance between the top of the tree and the line of sight of the observer is x.
To find the height of the tree, we need to first find x and then add it to the height of the observers line of sight from the ground.
Using SOHCAHTOA trigonometric function:
tan(20) = x/39.2
=> x = 39.2 * tan(20)
x = 39.2 * 0.364
x = 14.27m
Hence, the height of the tree is:
(14.27 + 1.98)m
16.25m
The tree is 16.25 m tall.