As shown in the figure, in △ ABC, the bisector of ∠ ABC and ∠ ACB intersects at point I. according to the following conditions, calculate the degree of ∠ BIC 1. If ∠ ABC = 60 °, ACB = 70 °, then ∠ BIC=____ 2. If ∠ ABC + ∠ ACB = 130 °, then ∠ BIC=____ 3. If ∠ a = 50 °, then BIC=____ 4. From the above calculation, what is the quantitative relationship between ∠ A and ∠ BIC? Please prove it

As shown in the figure, in △ ABC, the bisector of ∠ ABC and ∠ ACB intersects at point I. according to the following conditions, calculate the degree of ∠ BIC 1. If ∠ ABC = 60 °, ACB = 70 °, then ∠ BIC=____ 2. If ∠ ABC + ∠ ACB = 130 °, then ∠ BIC=____ 3. If ∠ a = 50 °, then BIC=____ 4. From the above calculation, what is the quantitative relationship between ∠ A and ∠ BIC? Please prove it

1. If ∠ ABC = 60 °, ACB = 70 °, then ∠ BIC=_ 115°___ 2. If ∠ ABC + ∠ ACB = 130 °, then ∠ BIC=_ 115°___ 3. If ∠ a = 50 °, then BIC=_ 115°___ 4. From the above calculation, what is the quantitative relationship between ∠ A and ∠ BIC

Given that the lengths of the two right sides of a right triangle are 3 and 4, the radius of its inscribed circle is______ ．

Let the two right sides of a right triangle be a and B, and the hypotenuse be C; the radius of the inscribed circle be r; then: a = 3, B = 4; according to the Pythagorean theorem, C = A2 + B2 = 5; r = a + B − C2 = 1. Therefore, the radius of the inscribed circle of a right triangle is 1

How to calculate the inscribed circle radius of a triangle (non right triangle) when the length of three sides is known
Given the length of three sides, how to find the radius of the inscribed circle of a triangle is an ordinary triangle, not a right triangle
For example, three sides a, B and C are 5, 6 and 7, and the formula is given

According to Helen's formula, we can calculate the area and the height of the bottom, and then we can calculate the radius of the inscribed circle according to the sine theorem sin a = 2R
We can also use cosine theorem
According to the cosine theorem, cosa = (C ^ 2 + B ^ 2-A ^ 2) / 2BC = 5 / 7
Then the height of AC side is (7 ^ 2-5 ^ 2) = 24
Ψ Sina = (2 radical 6) / 7 = 2R
Then the radius of inscribed circle r = (radical 6) / 7