# Edexel GCSE Maths Help please!!Watch

#1
0
2 years ago
#2
Try to focus on areas where you need to use a calculator, such as the quadratic formula or A = 1/2 ab sinC. Also revise the stuff that didn't come up in the first test, as it is more likely to come up in this one, hopefully.
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#3
Yeah, i need to do that but i just can't find anything to do. I know I cant do SOC CAH TOA and Trial and improvment which are going to come up i just cant do them also i just do not know whats going to pop up!
0
2 years ago
#4
(Original post by Richard.T)
Yeah, i need to do that but i just can't find anything to do. I know I cant do SOC CAH TOA and Trial and improvment which are going to come up i just cant do them also i just do not know whats going to pop up!
SOHCAHTOA - Form equation triangles of each bit:

O A O
S x H C x H T x A

Form the equation to find the right side, so if you're trying to find the hypotenuse (longest side of the triangle), and you're given an angle the adjacent (the other side touching the angle), then you'd do:

Length of Hypotenuse = Length of Adjacent / cos(Size of angle)

If it's the angle you're trying to find the size of the angle, then first do the same:

cos(x) = Length of Adjacent / Length of Hypotenuse

Then do:

cos-1 (Value you just obtained)

Trial and Improvement - Draw a table, with the columns being x, the equation in the question involving x, then a high / low (or H / L) column. In the latter column, if the value you get is higher than the number in the question, write H, and write L for the opposite.

For example:

x3 - x2 = 30

x is between 3 and 4

x x3 - x2 H/L
3 18 L
4 48 H

What you're meant to do here is do the same for a number in between 3 and 4. The midpoint (in this case 3.5) is your best bet:

x x3 - x2 H/L
3 18 L
4 48 H
3.5 30.625 H

Find another 1dp number between the lowest and highest numbers that give the closest values to 30 and do the same:

x x3 - x2 H/L
3 18 L
4 48 H
3.5 30.625 H
3.4 27.744 L

Now we've trapped it between two 1dp numbers. But we still have to do a 2dp number to see whether the answer is 3.4 or 3.5 due to rounding (despite if its bloody obvious or not). Once again, do the midpoint:

x x3 - x2 H/L
3 18 L
4 48 H
3.5 30.625 H
3.4 27.744 L
3.45 29.161 L

The value for 3.45 was less than 30, meaning that the value of x that gives 30 is between 3.45 and 3.5. Since the question asks for the answer as a 1dp number, the answer is 3.5.
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