Use the Product-To-Sum Formulas to Rewrite the Product as a Sum

question 40

Multiple Choice

Use the product-to-sum formulas to rewrite the product as a sum or difference. $10 \cos 45 ^ { \circ } \cos 20 ^ { \circ }$

• A) \(10 \left( \cos 25 ^ { \circ } + \cos 65 ^ { \circ } \right)\)
• B) \(\cos 25 ^ { \circ } + \cos 65 ^ { \circ }\)
• C) \(5 \left( \cos 65 ^ { \circ } - \cos 25 ^ { \circ } \right)\)
• D) \(5 \left( \cos 25 ^ { \circ } + \cos 65 ^ { \circ } \right)\)
• E) \(5 \left( \cos 65 ^ { \circ } + \sin 25 ^ { \circ } \right)\)

---

Definitions:

Secondary Circular Reaction

A stage in Piaget's theory of cognitive development where infants (around 4-8 months) repeat actions that affect their environment, showing an early understanding of cause and effect.

Sensorimotor Stage

A developmental phase from birth to about 2 years of age, in Jean Piaget's theory, where infants learn about their environment through their sensory and motor interactions.

Nonsymbolic Aspects

Elements or features not represented by symbols or not involving symbolic representation or thought, often relating to direct, concrete experiences.

Coordinate Sensations

involves the ability to integrate sensory information from different sources, leading to a unified perception of one's environment.