If cos x = sin(20 + x)° and 0° < x < 90°, the value of x is what?

we can change cos to sin by saying cosx=sin(90-x)

now we drop sin and make the angles equal (nothing needs to be added or subtracted since its in the first quadrant)

90-x=20+x+k.360kEZ (k is an element of set of integers) (we say k.360 if it's cos and sin and k.180 if it's tan)

-x-x=20-90+k.360kEZ

-2x=-70+k.360kEZ

divide all terms by -2

x=35-k.180kEZ

third option: 6x+8

step-by-step explanation:

we can see that the given question is a sum of series and the values of n vary from 0 to 3

the first term will be:

when n=0, [(0)*x+2] => (0+2) => 2

when n=1, [(1)*x+2] => (x+2) => x+2

when n=2, [(2)*x+2] => 2x+2

when n=4, [(3)*x+2] => 3x+2

so adding up all the terms will give us:

=2+x+2+2x+2+3x+2

=x+2x+3x+2+2+2+2

=6x+8

so,

third option is the correct answer ..

eveidence i thing that

step-by-step explanation: