Parallelogram has a certain area, its bottom and height______ (whether in inverse proportion) reason:______ ．

Parallelogram has a certain area, its bottom and height______ (whether in inverse proportion) reason:______ ．

Because the base × height of a parallelogram = the area of a parallelogram, the base and height of a parallelogram are inversely proportional

Judge whether the two quantities are in proportion, what proportion, and explain the reason (relation) the area of the parallelogram must be the base and height of the parallelogram
The value of a fraction is determined by its numerator and denominator
Difference must be subtracted and subtracted
A batch of coal can burn 36 days if it burns five tons a day, and 45 days if it burns four tons a day
Two reciprocal numbers

Base of parallelogram × height of parallelogram = area of parallelogram (definite)
Because the area of a parallelogram is fixed, the base and height of the parallelogram are inversely proportional
Numerator △ denominator = fractional value (certain)
Because the fraction is constant, the numerator is in direct proportion to the denominator
Subtracted - subtracted = difference (constant)
The subtracted is out of proportion to the subtracted
Days × tons of coal burned per day = one ton of coal (certain)
Because the quantity of a ton of coal is fixed, the number of days is inversely proportional to the ton of coal burned every day
A number x its reciprocal = 1
Because the product is definite, two reciprocal numbers are inversely proportional to each other

According to the data corresponding to the area and height of parallelogram in the table below, judge whether they are in proportion when the bottom is 6cm, and explain the reason
Parallelogram / square cm 6 12 18 24 30
Height / square cm 1 2 3 4 5

Area of parallelogram = base x height
The bottom is 6cm
Area = 6X1 = 6 bottom edge length = area △ height = 6 / 1 = 6 fixed
Area = 6x2 = 12 bottom edge length = area △ height = 12 / 2 = 6 fixed
Area = 6x3 = 18 bottom edge length = area △ height = 18 / 3 = 6 fixed
Area = 6x4 = 24 bottom edge length = area △ height = 24 / 4 = 6 fixed
Area = 5x6 = 30 bottom edge length = area △ height = 30 / 5 = 6 fixed
Therefore, the area is proportional to the height