Trigonometric Functions and Angles

Mrs. A explains how to find the exact values of sine and cosine for specific angles using special triangles and the CAST rule. The video covers finding the sine of 240° and the cosine of 135°, emphasizing the importance of related acute angles and quadrant rules. The process involves sketching angles, identifying related acute angles, and applying the CAST rule to determine the sign of the trigonometric function. Special triangles are used to find the exact values without a calculator.

What is the first step in finding the exact values of sine and cosine functions?

• Use a table of values

• Memorize the values

• Sketch the angle

• Use a calculator

In which quadrant does the angle 240° lie?

• Second quadrant

• Third quadrant

• First quadrant

• Fourth quadrant

What is the related acute angle for 240°?

• 60°

• 45°

• 90°

• 30°

What is the sine of 240°?

• -1/2

• √3/2

• -√3/2

• 1/2

Which rule helps determine the sign of trigonometric functions in different quadrants?

• Sine rule

• CAST rule

• Cosine rule

• Pythagorean theorem

What is the first step in finding the cosine of 135°?

• Use a table of values

• Memorize the values

• Sketch the angle

• Use a calculator

In which quadrant does the angle 135° lie?

• Fourth quadrant

• First quadrant

• Second quadrant

• Third quadrant

What is the related acute angle for 135°?

• 90°

• 60°

• 45°

• 30°

What is the cosine of 135°?

• 1/2

• -√2/2

• -1/2

• √2/2

What is the value of cosine 45°?

• √3/2

• √2/2

• 1/2

• 1