A student is painting a room at a constant rate. She is able to paint 2/5 of a room in 1/2 of an hour. How long does it take to
1 answer:
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Answer:
see explanation
Step-by-step explanation:
Using the sum/ difference → product formula
cos x - cos y = - 2sin( )sin (
)
sin x - sin y = 2cos ( )sin (
)
Given
(cosA - cosB)² + (sinA - sinB )²
= [ - 2sin()sin(
) ]² + [ 2cos(
)sin(
) ]²
= 4sin² ( )sin² (
) + 4cos² (
)sin² (
)
= 4sin² ( )[ sin² (
) + cos² (
) ← sin²x + cos²x = 1
= 4sin² ( ) × 1
= 4sin² ( ) = right side ⇒ proven