Trigonometry
Angle Sum and Difference, Double Angle and Half Angle Formulas
Find the exact value of:
If sinx = 4/8, find Cos (6x)

3√3

Step-by-step explanation:

If sinx = 4/8, find Cos (6x)

we need to first find cos

but applying trigonometry rule

sin²x+cos²x = 1

sinx = 4/8

sin²x = (4/8)² = 4²/8² = 16/64

from the rule

cos²x= 1 -sin²x = 1-16/64 = 64-16/64 = 48/64 = 3/4

cos²x = 3/4

cos x = √3/4 = √3/2

cos 6x = 6 x √3/2 = 3√3

step-by-step explanation:

step 1: solve one of the equations for one of the variables. let's solve the first equation for y:

step 2: substitute that equation into the other equation, and solve for x.

step 3: substitute x = 4 x = 4 x=4 into one of the original equations, and solve for y.

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