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Learn how to apply the Pythagorean Theorem to find areas, side lengths, and diagonal distances in squares and triangles. Discover shortcuts and practical applications to simplify calculations in geometry lessons.
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8th Grade Math 1st Period Nov. 1, 2012
No HW Review; Start Warm-Up Find the areas of the following: 1. 2. 3. 4. 5.
Warm-Up: Answers Find the areas of the following: 1. 2. 3. 4. 5. What operation could be applied to the area in #5 to get the side length of the square? A = 2 square units A = 1 square unit A = 4 square units A = 5 square units A = 1 square unit
So, to find the diagonal distance between two points, you can … • Draw a line segment between the points. • Make a square with the segment as a side. • Find the area of the square. • Take the square root of the area.
But … Do We Have to Make the Square Each Time?
No! Notice that … = making + =
If we remember our original line segment … is the hypotenuse of and we call the side lengths a, b, and c … a2 c b a + = b2 c2
That is, we can find … the square of the hypotenuse by adding the squares of the legs c2 b2 a2 This fact is known as the Pythagorean Theorem!
Looking for length of the hypotenuse a2 + b2 = c2 152 + 202 = x2 225 + 400 = x2 625 = x2 25 = x Using the Pythagorean Theorem x 15 20
Looking for length of a leg a2 + b2 = c2 62 + x2 = 102 36 + x2 = 100 -36-36 x2 = 64 x = 8 Using the Pythagorean Theorem 10 6 x
Looking for the diagonal distance a2 + b2 = c2 32 + 42 = x2 9 + 16 = x2 25 = x2 5 = x Using the Pythagorean Theorem x 3 4
HW (Front & Back of the Same WS) • Applications #1-2, 5-6 (circled) • Using the Pythagorean Theorem in Word Problems #1 (circled)
8th Grade Math 2nd Period Nov. 1, 2012
No HW Review; Start Warm-Up Find the areas of the following: 1. 2. 3. 4. 5.
Warm-Up: Answers Find the areas of the following: 1. 2. 3. 4. 5. What operation could be applied to the area in #5 to get the side length of the square? A = 2 square units A = 1 square unit A = 4 square units A = 5 square units A = 1 square unit
So, to find the diagonal distance between two points, you can … • Draw a line segment between the points. • Make a square with the segment as a side. • Find the area of the square. • Take the square root of the area.
But … Do We Have to Make the Square Each Time?
No! Notice that … = making + =
If we remember our original line segment … is the hypotenuse of and we call the side lengths a, b, and c … a2 c b a + = b2 c2
That is, we can find … the square of the hypotenuse by adding the squares of the legs c2 b2 a2 This fact is known as the Pythagorean Theorem!
Looking for length of the hypotenuse a2 + b2 = c2 152 + 202 = x2 225 + 400 = x2 625 = x2 25 = x Using the Pythagorean Theorem x 15 20
HW (Front & Back of the Same WS) • Applications #1-2, 5-6 (circled) • Using the Pythagorean Theorem in Word Problems #1 (circled)
8th Grade Math 4th Period Nov. 1, 2012
No HW Review; Start Warm-Up Find the areas of the following: 1. 2. 3. 4. 5.
Warm-Up: Answers Find the areas of the following: 1. 2. 3. 4. 5. What operation could be applied to the area in #5 to get the side length of the square? A = 2 square units A = 1 square unit A = 4 square units A = 5 square units A = 1 square unit
So, to find the diagonal distance between two points, you can … • Draw a line segment between the points. • Make a square with the segment as a side. • Find the area of the square. • Take the square root of the area.
But … Do We Have to Make the Square Each Time?
No! Notice that … = making + =
If we remember our original line segment … is the hypotenuse of and we call the side lengths a, b, and c … a2 c b a + = b2 c2
That is, we can find … the square of the hypotenuse by adding the squares of the legs c2 b2 a2 This fact is known as the Pythagorean Theorem!
Looking for length of the hypotenuse a2 + b2 = c2 152 + 202 = x2 225 + 400 = x2 625 = x2 25 = x Using the Pythagorean Theorem x 15 20
Looking for the diagonal distance a2 + b2 = c2 32 + 42 = x2 9 + 16 = x2 25 = x2 5 = x Using the Pythagorean Theorem x 3 4
HW (Front & Back of the Same WS) • Applications #1-2, 5-6 (circled) • Using the Pythagorean Theorem in Word Problems #1 (circled)