Answer:
Step-by-step explanation:
![1-2\sin^2x=\sin x\\\\\text{substitute}\ t=\sin x,\ t\in[-1,\ 1]\\\\1-2t^2=t\qquad\text{subtract t from both sides}\\\\-2t^2-t+1=0\qquad\text{change the signs}\\\\2t^2+t-1=0\\\\2t^2+2t-t-1=0\\\\2t(t+1)-1(t+1)=0\\\\(t+1)(2t-1)=0\iff t+1=0\ \vee\ 2t-1=0\\\\t+1=0\qquad\text{subtract 1 from both sides}\\\boxed{t=-1}\\\\2t-1=0\qquad\text{add 1 to both sides}\\2t=1\qquad\text{divide both sides by 2}\\\boxed{t=\dfrac{1}{2}}](https://tex.z-dn.net/?f=1-2%5Csin%5E2x%3D%5Csin%20x%5C%5C%5C%5C%5Ctext%7Bsubstitute%7D%5C%20t%3D%5Csin%20x%2C%5C%20t%5Cin%5B-1%2C%5C%201%5D%5C%5C%5C%5C1-2t%5E2%3Dt%5Cqquad%5Ctext%7Bsubtract%20t%20from%20both%20sides%7D%5C%5C%5C%5C-2t%5E2-t%2B1%3D0%5Cqquad%5Ctext%7Bchange%20the%20signs%7D%5C%5C%5C%5C2t%5E2%2Bt-1%3D0%5C%5C%5C%5C2t%5E2%2B2t-t-1%3D0%5C%5C%5C%5C2t%28t%2B1%29-1%28t%2B1%29%3D0%5C%5C%5C%5C%28t%2B1%29%282t-1%29%3D0%5Ciff%20t%2B1%3D0%5C%20%5Cvee%5C%202t-1%3D0%5C%5C%5C%5Ct%2B1%3D0%5Cqquad%5Ctext%7Bsubtract%201%20from%20both%20sides%7D%5C%5C%5Cboxed%7Bt%3D-1%7D%5C%5C%5C%5C2t-1%3D0%5Cqquad%5Ctext%7Badd%201%20to%20both%20sides%7D%5C%5C2t%3D1%5Cqquad%5Ctext%7Bdivide%20both%20sides%20by%202%7D%5C%5C%5Cboxed%7Bt%3D%5Cdfrac%7B1%7D%7B2%7D%7D)
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Answer:
$40
Step-by-step explanation:
Find the original price by dividing 28 by 0.7
28/0.7
= 40
So, the original price was $40
Answer:
C. 5
Step-by-step explanation:
OXA is a 3-4-5 right triangle, so the circle radius is OA = 5.
_____
By the Pythagorean theorem,
AO² = OX² +AX² = 3² +4² = 9 +16 = 25
AO = √25 = 5 . . . . circle radius
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<em>Comment on Pythagorean triples</em>
The triple of integers (3, 4, 5) is the smallest triple of integers that satisfies the relation of the Pythagorean theorem. The next smallest set is (5, 12, 13). These, and a few other similar triples such as (7, 24, 25) and (8, 15, 17) are often used in algebra and geometry problems because they make the numbers work out nicely. It is worthwhile to learn to recognize these.
