Answer:
D
Step-by-step explanation:
Parallel lines have the same gradient.
A line with a slope of zero is a horizontal line. Although two lines that have a slope of zero will result in two parallel lines, not all parallel lines are horizontal lines. Since the question is asking for which statement <u>must</u> be true, option A is incorrect.
If the slopes of two lines are negative reciprocals, they are perpendicular to each other. This is because the product of the gradients of 2 perpendicular lines is -1. Let the gradient of the first line be A and the other be B.
AB= -1


Thus, option B is incorrect too.
Undefined slopes gives vertical lines. Like option A, if two lines have an undefined slope, they will be parallel to each other. However since parallel lines are nit necessarily vertical lines, option C is also incorrect.
A trapezoid is isosceles if and only if
(1) The base angles are congruent
(2) The diagonals are congruent
(3) The opposite angles are supplementary
So the description does not guarantee that a trapezoid is isoceles for "Congruent bases".
Answer: Number of bags of 8. = 33
Number of bags of 10. = 31
Step-by-step explanation:
Let x = Number of bags of 8.
y = Number of bags of 10.
As per given.
(i)
(ii)
Put value of x from (ii) in (i)
Put this in (i), x= 31+2=33
Hence,
Number of bags of 8. = 33
Number of bags of 10. = 31