Question

треугольник АВС угол С равен 90 градусов, АС равен 7,ВС равен 7 из корня 3, найти косинус угла А, помогите ​

Answer 1

Ответ:

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Объяснение:

Answer 2

Problem Analysis

We are given a triangle ABC with angle C equal to 90 degrees, AC equal to 7, and BC equal to the square root of 3. We need to find the cosine of angle A.

Solution

To find the cosine of angle A, we can use the cosine rule, which states that in a triangle with sides a, b, and c, and angle C opposite side c, the following equation holds:

c^2 = a^2 + b^2 - 2ab * cos(C)

In our case, we have: - c = BC = √3 - a = AC = 7 - b = AB (unknown) - C = 90 degrees

Substituting these values into the cosine rule equation, we get:

(√3)^2 = 7^2 + b^2 - 2 * 7 * b * cos(90)

Simplifying the equation, we have:

3 = 49 + b^2 - 14b * cos(90)

Since cos(90) = 0, the equation becomes:

3 = 49 + b^2

Rearranging the equation, we get:

b^2 = 3 - 49 b^2 = -46

Since we cannot take the square root of a negative number, it means that there is no real solution for the length of side AB. Therefore, we cannot find the cosine of angle A in this case.

Answer

In the given triangle ABC with angle C equal to 90 degrees, AC equal to 7, and BC equal to the square root of 3, it is not possible to find the cosine of angle A because there is no real solution for the length of side AB.