What are the usages of length units in English?

What are the usages of length units in English?

meter
feet
inch
mini meter
etc...

What is the unit of length of feet?

It means foot,
1 foot = 12 inches = 0.3048m = 30.48cm

foot

Foot: [fut] is English
n. Feet
Morphological changes:
Noun plural: feet verb past tense: footed past participle: footed present participle: footing third person singular: feet

Degree minute second conversion 1 / 30 ° = () ′ 36.81 ° = () ° () ′ () ″

1/30°=（2）′
36.81°=（38）°（48）′（36）″

Let f (x) > 0 be a and B = {x | 1

f(x)=ax²-2x-2a>0
Then there are: a [x - (√ a) / a] & sup2; > 2A
If a > 0
Then x - (√ a) / a] & sup2; > 2
So x > √ 2 + (√ a) / A
Or X

7.8.9.10.11.12.13.14 how to add up is equal to 31

The questions are not detailed enough to answer
For example, how many rows, how many columns, how many numbers add up

Given vector a = (3 / 2, SiNx) vector b = (cosx, 1 / 3), and vector a is parallel to vector B, what is the acute angle X?

Vector a = (3 / 2, SiNx) vector b = (cosx, 1 / 3), and vector a is parallel to vector B
So (3 / 2) * (1 / 3) - cosx * SiNx = 0
So 1 / 2 = sinxcosx
So 1 = sin2x
So 2x = 2K π + π / 2
So x = k π + π / 4
And X is an acute angle
So x = π / 4

Simple calculation ^ o of 55 × 25 + 25 × 45^

If the parabola C1: y ^ 2 = 4x rotates anticlockwise from PI / 2 to C2 around the focus, C1 and C2 intersect a and B, and the curve of its siege is like a number leaf, then the equation of the straight line AB is____
The answer is y = X-1
Why?

The parabola is symmetric
Therefore, 90 degrees counterclockwise rotation can also be understood as axisymmetry by a straight line with a slope of 1 (45 degrees)
And because (1,0) is the original focus and the new focus, so (1,0) is on this axis of symmetry, so y = x + m passes (1,0)
So y = X-1

What is the quotient of the difference between the product of 8.5 and 4 times 0.875 divided by 4 / 1

(8.5-4 × 0.875) △ 1 / 4
=(8.5-3.5) △ 1 / 4
=5 △ 1 / 4
=20