In a right-angled triangle ABC with right angle C, the tangent of the outer angle at the vertex A

In a right-angled triangle ABC with right angle C, the tangent of the outer angle at the vertex A is −3√10 / 20, side BC is 3. Find side AB.

The BAC angle is adjacent to the ВAD angle, the sum of which is 1800, then the BAC angle = (180 – ВAD).

tgBAC = tg (180 – BAD) = -tgBAC = 3 * √10 / 20.

The tangent of an acute angle of a right-angled triangle is equal to the ratio of the length of the opposite leg to the length of the adjacent leg.

tgВАС = ВС / АС.

АС = ВС / tgBAC = 3 / (3 * √10 / 20) = 20 / √10 = 2 * √10 cm.

In a right-angled triangle ABC, according to the Pythagorean theorem, AB^2 = BC^2 + AC^2 = 9 + 40 = 49.

AB = 7 cm.

Answer: The length of the hypotenuse AB is 7 cm.



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