Answer:

Step-by-step explanation:
Recall the mnemonics SOH CAH TOA.
SOH means the Sine ratio is Opposite over Hypotenuse.
This implies that;

The side opposite to angle A is 4cm and the hypotenuse is 5cm.

Answer:
Option C and D that is y= tan x and y= cot x
Step-by-step explanation:
The range is the values of y means the values that y can take in a function:
So, range of tan x and cot x are all real numbers.
Period of tan x is 
Period of cot x is 
Option A and B that is secx and csc x are discarded
Answer:
x=30
Step-by-step explanation:
You have to isolate for x. This means you need to somehow get x on one side of the equation all alone. In this case it is x-9=21 which means some unknown number x with 9 subtracted from it is equal to 21. When we bring the -9 over to the other side to get the x all alone, we have to switch the sign of the -9 so it becomes +9. This means x=21+9, and if you add that you'll get 30!
12+4+9+13+7+11+5+2+_+_ /10= 8
x10 both sides
12+4+9+13+7+11+5+2+_+_=80
63+_+_=80
-63 both sides
_+_= 17
any two numbers that add up to 17 can go in the planks
7,10