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### Introduction to Angles

00:09:55Salman KhanWhat an angle is. Angles in a circle. Complementary and supplementary angles.

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### Angles Part 2

00:09:04Salman KhanMore on complementary and supplementary angles. Introduction to opposite angles.

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### Circles: Radius, Diameter, and Circumference

00:11:05Salman KhanUnderstanding the relationship between the radius diameter and circumference of a circle.

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### The Pythagorean Theorem II

00:09:36Salman KhanMore Pythagorean Theorem examples. Introduction to 45-45-90 triangles.

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### Intro to 30-60-90 Triangles

00:09:39Salman KhanA few more 45-45-90 examples and an introduction to 30-60-90 triangles.

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### Heron's Formula

00:04:43Salman KhanUsing Heron's Formula to determine the area of a triangle while only knowing the lengths of the sides.

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### Part 2 of Proof of Heron's Formula

00:12:08Salman KhanShowing that the expression in part 1 is identical to Heron's Formula.

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### An Inscribed Angle is Half of a Central Angle that Subtends the Same Arc

00:14:16Salman KhanShowing that an inscribed angle is half of a central angle that subtends the same arc.

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### Area of Inscribed Equilateral Triangle (Some Basic Trig Used) 2

00:11:39Salman KhanProblem that requires us to figure out the area of an equilateral triangle inscribed in a circle (A little trigonometry used).

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### Right Triangles Inscribed in Circles

00:05:35Salman KhanProof showing that a triangle inscribed in a circle having a diameter as one side is a right triangle.

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### Area of Inscribed Equilateral Triangle (Some Basic Trig Used)

00:04:36Salman KhanArea of Diagonal Generated Triangles of Rectangle are Equal.

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