Question

Write the expression as either the sine, cosine, or tangent of a single angle.

cosine of pi divided by five times cosine of pi divided by seven plus sine of pi divided by five times sine of pi divided by seven.

Answer 1

perhaps you could use the draw option to write it

Answer 2

\[\cos \left( \frac{ π }{ 5 } \right)\cos \left( \frac{ π }{ 7 } \right) + \sin \left( \frac{ π }{ 5 } \right)\sin \left( \frac{ π }{ 7 } \right)\]

Answer 3

would you start by multiplying the first two together and the second two together?

Answer 4

probably, been a while since i have worked with angles like this

Answer 5

ok... so this looks like the cos identity for the difference of 2 angles

\[\cos(A - B) = \cos(A)\cos(B) + \sin(A)\sin(B)\]

hopefully this helps

Answer 6

so you know the angles... just substitute both angles into the left side of the equation and simplify

Answer 7

\[\cos \left( \frac{ \pi }{ 5 } - \frac{ \pi }{ 7 }\right)\]
so its this? @campbell_st

Answer 8

that p is suppose to be pi....

Answer 9

thats it... just simplfy the 2 fractions...

its like

1/5 - 1/7 but you need pi in the numerator

Answer 10

or

\[\pi \times (\frac{1}{5} - \frac{1}{7}) = \]

Answer 11

\[\cos \left( \frac{ 7\pi }{ 35 } - \frac{ 5\pi }{ 35 } \right)\]

Answer 12

yep... just simplify that for the answer

Answer 13

\[\cos \left( \frac{ 2\pi }{ 35 } \right)\]
this cant be simplified any further can it?

Answer 14

no thats as far as you can simplify unless you solve

Answer 15

okay thank you

Answer 16

yw