# Worksheet: Angle Sum and Difference Identities

In this worksheet, we will practice deriving the angle sum and difference identities, graphically or using the unitary circle, and using them to find trigonometric values.

**Q4: **

Evaluate .

- A
- B
- C
- D

**Q5: **

In triangle , and are acute angles, where and . Without using a calculator, find the value of .

- A
- B
- C
- D
- E

**Q6: **

Let us consider the two shown figures, each showing two points on the unit circle.

How is the figure on the right obtained from the figure on the left?

- Aby rotating by an angle of about the origin
- Bby rotating by an angle of about the origin
- Cby rotating by an angle of about the origin
- Dby rotating by an angle of about the origin
- Eby rotating by an angle of about the origin

What can you say about the triangles and ?

- AThey are congruent.
- BThey are similar.
- CThey are equilateral.
- DThey are different.
- EThey are isosceles.

Find the coordinates of , , , and .

- A, , ,
- B, , ,
- C, , ,
- D, , ,
- E, , ,

Calculate the lengths of and .

- A,
- B,
- C,
- D,
- E,

Use what you found in the previous questions to find an expression for .

- A
- B
- C
- D
- E

**Q7: **

is a triangle where and . Find without using a calculator.

- A
- B0
- C
- D

**Q8: **

Find given and where and are two positive acute angles.

- A0
- B
- C
- D

**Q9: **

Using the relation , find an expression for .

- A
- B
- C
- D

**Q10: **

Find given and where and are acute angles.

- A
- B
- C
- D
- E

**Q11: **

Given that , where is a positive acute angle, determine without using a calculator.

- A
- B
- C
- D

**Q12: **

Which of the following is equivalent to ?

- A
- B
- C
- D

**Q13: **

Find given and where and are acute angles.

- A
- B
- C
- D0

**Q14: **

Given that and , where and are two positive acute angles, determine .

- A
- B
- C
- D

**Q15: **

Given that and , where and are two positive acute angles, determine .

- A
- B
- C
- D

**Q16: **

Find given and where and are acute angles.

- A
- B
- C0
- D

**Q17: **

Using the relations and , find an expression for .

- A
- B
- C
- D

**Q18: **

Find given and where and are acute angles.

- A
- B
- C
- D
- E

**Q19: **

Given that and , where and are two positive acute angles, determine .

- A
- B
- C
- D1

**Q20: **

Using the relation , find an expression for .

- A
- B
- C
- D

**Q21: **

In triangle , and are acute angles, where , and . Without using a calculator, find the value of .

- A
- B
- C
- D

**Q22: **

Given that , where is a positive acute angle, determine without using a calculator.

- A
- B
- C
- D

**Q23: **

Evaluate , given .

**Q24: **

Find given and where and are two positive acute angles.

- A
- B
- C
- D
- E

**Q25: **

Find the value of given and where and are two positive acute angles.

- A
- B
- C
- D
- E