Question

Difficulty: EasyRight Triangles and the Pythagorean Theorem

In the figure, triangle RSTRST is a right triangle with the right angle at vertex SS. If the length of side RSRS is 88 and the length of side STST is 1515, what is the length of the hypotenuse RTRT?

  1. A
    7
  2. B
    13
  3. 17Answer
  4. D
    23

Answer

17
According to the Pythagorean theorem, the square of the hypotenuse is equal to the sum of the squares of the legs: RT2=RS2+ST2RT^2 = RS^2 + ST^2. Substituting the given values yields RT2=82+152=64+225=289RT^2 = 8^2 + 15^2 = 64 + 225 = 289. Taking the square root of 289289 gives RT=17RT = 17.

Step-by-Step Solution

1
Set up the Pythagorean theorem for right triangle RSTRST.
RS2+ST2=RT2RS^2 + ST^2 = RT^2
In any right triangle, the sum of the squares of the legs equals the square of the hypotenuse.
2
Substitute the given side lengths into the equation.
82+152=RT28^2 + 15^2 = RT^2
The legs of the triangle are RS=8RS = 8 and ST=15ST = 15.
3
Calculate the squares and sum them.
64+225=289=RT264 + 225 = 289 = RT^2
82=648^2 = 64 and 152=22515^2 = 225. Adding them gives 289289.
4
Take the square root of both sides to find the length of the hypotenuse.
RT=289=17RT = \sqrt{289} = 17
The length must be a positive value, and 289\sqrt{289} simplifies to 1717.

Key Concept

The Pythagorean theorem states that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the legs: a2+b2=c2a^2 + b^2 = c^2.
Estimated Time:45s
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