Answer:
D. Pythagorean
Step-by-step explanation:
Given the identity
cos²x - sin²x = 2 cos²x - 1.
To show that the identity is true, we need to show that the left hand side is equal to right hand side or vice versa.
Starting from the left hand side
cos²x - sin²x ... 1
According to Pythagoras theorem, we know that x²+y² = r² in a right angled triangle. Coverting this to polar form, we have:
x = rcostheta
y = rsintheta
Substituting into the Pythagoras firnuka we have
(rcostheta)²+(rsintheta)² = r²
r²cos²theta+r²sin²theta = r²
r²(cos²theta+sin²theta) = r²
(cos²theta+sin²theta) = 1
sin²theta = 1 - cos²theta
sin²x = 1-cos²x ... 2
Substituting equation 2 into 1 we have;
= cos²x-(1-cos²x)
= cos²x-1+cos²x
= 2cos²x-1 (RHS)
This shows that cos²x -sin²x = 2cos²x-1 with the aid of PYTHAGORAS THEOREM
I think it is B or A, but manly A
Answer:
Step-by-step explanation:
1a. 25/50 =x/100
25*100= 2500/50= 50
A= 50%
1b. 35/40 = x/100
35*100= 3500/40= 87.5
A=87.5%
2a. 15/20= x/100
20*5= 100; 15*5= 75
A=75%
2b. 25/70= x/100
25*100= 2500/70= 35.71
A=35.71
3a. 15/80= x/100
15*100= 1500/80=18.75
A=18.75%
3b. 30/60= x/100
30/60= 1/2;1/2=0.5;0.5= 50%
A=50%
4a. 70/80 =x/100
70*100=7000/80 =87.5
A=87.5
4b.30/60 = 50% ( same as question #3b)
D is correct. U is incenter of the triangle.
