Answer:
steps below
Step-by-step explanation:
Are you going to solve the value of A or just a proof the equation
cos 2A = cos² A - sin² A
2cos²A-cos2A-1 = 2cos²A - (cos² A - sin² A) - 1 = cos² A + sin² A - 1
2cos²A-cos2A-1 = 1 - 1 = 0
A: 90° or 270° or 450° .....
2x20
1x40
4x10
5x8
All integers these multiply to 40
Answer:
30, 40, 50 which is choice C
Step-by-step explanation:
Square the smaller two values (30 and 40)
30^2 = 900
40^2 = 1600
then add those results
900+1600 = 2500
Notice how 50^2 = 2500 as well. This shows us that 30^2 + 40^2 = 50^2 is a true equation. Both sides lead to the same result 2500. Therefore, a triangle with sides 30, 40, 50 is a right triangle. This is based on the 3-4-5 pythagorean triple, just each side has been multiplied by 10.
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