Prove the Pythagorean Theorem.

Given that Upper Delta ABC is a right​ triangle, prove asquaredplusbsquaredequalscsquared.
A
B
C
a
b
c
q
r
D
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Part 1
What is the first step to be​ performed?
A.
Use the corollary​ 'Geometric Mean in Similar Right​ Triangles: Hypotenuse.'
B.
Use the Angle Bisector Theorem.
C.
Use the corollary​ 'Geometric Mean in Similar Right​ Triangles: Legs.'
D.
Use the Hinges Theorem.

1 answer

To prove the Pythagorean Theorem in a right triangle \( \Delta ABC \) where \( C \) is the right angle, we can start by establishing similar triangles within the figure. The first step that aligns with this method is:

C. Use the corollary 'Geometric Mean in Similar Right Triangles: Legs.'

This involves demonstrating relationships between the right triangle and the segments created by dropping a perpendicular from point \( C \) to \( AB \). By utilizing similar triangles, we can derive the necessary relationships between the lengths of the sides \( a \), \( b \), and \( c \).

To outline further steps after this initial decision, you would typically proceed as follows:

  1. Drop a perpendicular from \( C \) to line segment \( AB \), calling the point of intersection \( D \).
  2. Show that triangles \( \Delta ACD \) and \( \Delta BCD \) are similar to triangle \( \Delta ABC \) and to each other.
  3. Establish the relationships \( AD^2 = AC^2 - DC^2 \) and \( BD^2 = BC^2 - DC^2 \) based on the similarities of triangles.
  4. Combine these relations to come to the conclusion that \( a^2 + b^2 = c^2 \).

By relying on the properties of similar triangles and their proportions, we can ultimately arrive at the proof for the Pythagorean Theorem.