The hypotenuse of a right-angled triangle is 13, one of the legs is 5. Find the elements of the triangle.
Let’s define the second leg of a right-angled triangle by the Pythagorean theorem.
AB ^ 2 = BC ^ 2 – AC ^ 2.
AB ^ 2 = 13 ^ 2 – 5 ^ 2 = 169 – 25 = 144.
AB = 12 cm.
The leg of a right-angled triangle is equal to the square root of the product of the hypotenuse and the projection of this leg to the hypotenuse.
AC = √ (BC * CH).
AC2 = BC * CH.
CH = 52/13 = 25/13 = 1 (12/13) cm.
AB ^ 2 = BC * BH.
BH = 144/13 = 11 (1/13) cm.
AH = √ (BH * CH) = √ (25/13 * 144/13) = 60/13 = 4 (8/13) cm.
The median AM of the ABC triangle is equal to half the length of the hypotenuse.
AM = BC / 2 = 13/2 = 6.5 cm.
Cos ACB = AC / BC = 5/13.
Angle ACB Arccos 5/13.
Cos ABC = AB / BC = 12/13.
Angle ABC Arccos 12/13.
Answer: AB = 12, AH = 4 (8/13), CH = 1 (12/13), BH = 11 (1/13), AM = 6.5.