If the angle c = 90 degrees, (a + b) * (a + b) = 12 and C = 2 in the right triangle ABC, then the s triangle ABC =?

If the angle c = 90 degrees, (a + b) * (a + b) = 12 and C = 2 in the right triangle ABC, then the s triangle ABC =?

（a+b)^2=a^2+2ab+b^2=c^2+2ab=12
Because, C ^ 2 = 4
So AB = 4
S△ABC=1/2ab=2

In the right triangle ABC, the opposite sides of ∠ C = 90 °, a, B and C are a, B and C respectively
1, if ∠ a = 30 ° and C = 24, find the height h on the side of C
2. If a, B and C are continuous integers, find a + B + C

（1）∵∠A=30°,c=24,
A = 12, B = 12, radical 3,
Then (1 / 2) AB = (1 / 2) C × h,
The solution is: H = 6, root sign 3;
(2) Let a = X-1, B = x, C = x + 1,
Then: (x-1) ^ 2 + x ^ 2 = (x + 1) ^ 2,
The solution is: x = 4, that is, a = 3, B = 4, C = 5,
So a + B + C = 12
(1 / 2) is half

In the triangle ABC, ∠ C = 90 degrees, ab = 5, and the circumference is 12, what is the radius of its inscribed circle
the sooner the better

Radius of inscribed circle 1 1 / 2 (12-2 * 5) = 1

In RT △ ABC, ∠ C = 90, the length of oblique side is equal to 10, ⊙ o is the inscribed circle of triangle ABC, the radius is equal to 2, find the perimeter of △ ABC

Let ⊙ O and RT △ ABC be tangent to D, e and C on the edges of AC, AB and BC respectively
AD=AE,BF=BE,CD=CF=2
Δ ABC perimeter = AC + AB + BC = CD + AD + AE + be + BF + CF = 2CD + 2 (AE + be) = 2CD + 2Ab = 2 * 2 + 2 * 10 = 24

From 1,2,3 , 19.20, how many such arithmetical sequences are there?

2*(9+9+8+8+7+7+6+6+5+5+4+4+3+3+2+2+1+1)=180
The first number is 1, and nine groups can be found
The first number is 2, there are also 9 groups, and so on, until 18
Multiply by two, because each sequence is in turn an arithmetic sequence

The general term formula and the 20th term of arithmetic sequence 8,5,2
If someone can give me a clear answer, it's best. Because it's different from my formula, so I ask a question

Tolerance d = a2-a1 = 5-8 = - 3; A1 = 8, then an = 8 + (- 3) (n-1) = 11-3n, substituting n = 20, then A20 = 11-60 = - 49

Write out the general term formula of the arithmetic sequence 10,8,6,... And find out the 20th term of the sequence

The tolerance is - 2, the first term is 10, so the general term is an = 10-2 (n-1) = 12-2n, so the 20th term is A20 = 12-80 = - 68

(1) Find arithmetic sequence 8, 5, 2 (2) judge whether - 401 is an arithmetic sequence - 5, - 9, - 13 What's your item? If yes, which item is it? If not, explain the reason

(1) Arithmetic sequence 8, 5, 2 Among them, A1 = 8, d = 5-8 = - 3, n = 20 ∥ an = a1 + (n-1) d = - 3N + 11 ∥ A20 = 11-3 × 20 = - 49 (4 points) (2) arithmetic sequence - 5, - 9, - 13 Where, A1 = - 5, d = - 9 - (- 5) = - 4 ∧ an = - 5 + (n-1) × (- 4) = - 4N-1, let - 401 = - 4N-1, then & nbsp; n = 100 ∧ - 401 is the 100th term of the sequence (8 points)

Arithmetic sequence 8, 5, 2 Item 20 of the report is______ ．

Arithmetic sequence 8, 5, 2 If the first item A1 = 8, tolerance d = - 3, then an = a1 + (n-1) d  A20 = a1 + (20-1) (- 3) = - 49, so the answer is: - 49

The sum of the first 20 terms of the arithmetic sequence 2,5,8,11?

The tolerance is 3
Item 20 is 2 + 3 × (20-1) = 59
therefore
The sum of the first 20 terms = (2 + 59) × 20 △ 2 = 610