Question

Trigonometry yr 10 , pls help fast

Answer 1

Let's consider what the question asks for:

--> value of y when x = 45

In the equation: we need to find the value of 'a' and 'b'

--> lets plug our other known value to find 'a' and 'b'

--> let's use the value of x = 90 and y = 4

--> as cos(x) will equal zero and we can find the value for 'b'

`y=a*cos(x)+b\\4=a*cos(90)+b\\4=0+b\\b=4`

--> having found 'b', let's find 'a' with any other set of value

--> lets use y = 10 when x = 0

`10=a*cos(0)+4\\10=a*1+4\\10=a+4\\a=6`

Having found 'a' and 'b':

--> let's plug in 'x = 45' in the equation to find its corresponding y-value

`y=6*cos(45) +4\\\\y = 6 * (√(2) )/(2) +4= 4 + 3√(2)`

Thus the value of y, when x = 45

==> Answer:

`4 + 3√(2)`