Find the sides of a right-angled triangle if you know that its hypotenuse is 10 cm
Find the sides of a right-angled triangle if you know that its hypotenuse is 10 cm and one acute angle is 2 times larger than the other.
First, find the sharp corners of this triangle. Since one angle is twice as large as the other angle, we will express them as follows:
x = angle ∠B;
2x – the value of the angle ∠A;
90 ° is the degree measure of the angle ∠С;
180 ° = the sum of all the angles of the triangle;
x + 2x + 90 = 180;
3x = 180 – 90 = 90;
x = 90/3 = 30;
∠В = 30 °;
∠А = 2 30 = 60 °.
Using the sine of an acute angle, you can find the side of the AC:
sin B = AC / AB;
AC = AB sin B;
sin 30 ° = ½;
AC = 10 ½ = 5 cm.
Now, according to the Pythagorean theorem, you can find the length of the second leg:
AB ^ 2 = BC ^ 2 + AC ^ 2;
BC ^ 2 = AB ^ 2 – AC ^ 2;
BC ^ 2 = 10 ^ 2 – 52 ^ = 100 – 25 = 75;
BC = √75 = 8.66 cm.
Answer: the legs of the triangle are 5 cm and 8.66 cm.