Me! if 0 < f ≤ 90 and cos(22f - 1) = sin(7f + 4), what is the value of f?
a- f =3
b- f =4
c- f=5
d- f=6

Step-by-step explanation:

A

Step-by-step explanation:

We know that x is an angle where 0<x<=90

so from the above equation

   -----(i)

and  -----(ii)

so we can find the value of f by solving these two equations.

by putting value of x from (i) into (ii)

So option A is the correct answer.

step-by-step explanation:

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places