Given that a, B and C are three sides of △ ABC, and A2 + B2 + C2 = AB + AC + BC, then △ ABC is () A. Isosceles triangle B. right triangle C. equilateral triangle D. isosceles right triangle

Given that a, B and C are three sides of △ ABC, and A2 + B2 + C2 = AB + AC + BC, then △ ABC is () A. Isosceles triangle B. right triangle C. equilateral triangle D. isosceles right triangle

The original formula can be reduced to 2A2 + 2B2 + 2c2 = 2Ab + 2Ac + 2BC, that is, A2 + B2 + C2 + A2 + B2 + c2-2ab-2ac-2bc = 0; according to the complete square formula, we can get: (a-b) 2 + (C-A) 2 + (B-C) 2 = 0; from the properties of non negative numbers, we can know that A-B = 0, C-A = 0, B-C = 0; that is, a = b = C. so △ ABC is an equilateral triangle, so we choose C

What are the words and phrases that describe and describe mood in English?

Admiring Adore AgreeableAnticipate Ardent Aroused Assure Avid Bliss Brave Calm Capable Careful Caring CautiousCentered Charitable Comfort Compassionate Concern Considerate Consoled Contented Delighted...

Mathematics of senior one, equation of straight line and circle
If the line L moves 2 units along the positive direction of x-axis, and then 1 unit along the negative direction of y-axis, and returns to the original position, then the slope k of the line L=

Let l ax + by + C = 0, according to the condition a (X-2) + B (y + 1) + C = 0
The simultaneous solution of the two equations gives B = 2A, so k = A / b = 1 / 2

How to say holiday life in English?

Holiday life

The numerator and denominator of a true fraction are two continuous natural numbers. If 3 is added to the denominator, the fraction will be about 4 / 5. The original fraction is many

Primary school methods:
The numerator denominator is a continuous natural number. After adding 3 to the denominator, the denominator is 1 + 3 = 4 more than the numerator
The denominator of the new fraction is 4 * 5 = 20, and the numerator is 4 * 4 = 16
The original denominator is 20-3 = 17
The score is 16 / 17

The plural of a noun can be preceded by the

Can add the, as long as it is special, all nouns can, regardless of the singular and plural
The books on the desk are mine
The air in the room is not fresh.

Given that a = 4 and B = 8, the angle between a and B is 150 ° to calculate 1 >, (a + 2b) (2a-b) 2 >, 4a-2b

-- the first question is a lot wrong

Find primary English verb phrases

/>underbuy underbought underbought undercut undercut undercut underfeed underfed underfed undergo underwent undergone underlay underlaid underlaid underlet underlet underlet underlie underlay underlai...

In △ ABC, ∠ BAC = 100 ° if de and FG divide AB and AC vertically, then ∠ EAF=______ ．

∵∠ BAC = 100 °, ∵ B + ∠ C = 180 ° - 100 ° = 80 °, ∵ de and FG vertically divide AB and AC respectively, ∵ BAE = ∠ B, ∵ CAF = ∠ C, ∵ BAE + ∠ CAF = 80 °, ∵ EAF = 100 ° - 80 ° = 20 °. So the answer is: 20 °

That book is new.I am a boy.She is a girl.Is The dictionary on the desk

Those books are new.We are boys.They are girls.Are these dictionaries on the desk?