Answer:
3
Step-by-step explanation:
私は怠惰なのでグーグルで調べました
Answer:
90°
Step-by-step explanation:
90°
Answer:
B. (-0.73, 0), (2.73, 0)
Step-by-step explanation:
vertex form of a parabola
y = a(x-h)^2 +k
y = a(x-1)^2 -9
substitute the point in to find a
-6 = a (0-1) ^2 -9
-6 = a *1 -9
add 9 to each side
-6+9 = a -9+9
3 =a
y = 3(x-1)^2 -9
FOIL
y = 3(x-1)(x-1) -9
y = 3(x^2-2x+1) -9
distribute
y = 3x^2-6x+3-9
combine like terms
y = 3x^2 -6x -6
factor out 3
y= 3(x^2 - 2x -2)
set = 0
0 = 3(x^2 - 2x -2)
x^2 - 2x -2 =0
using the quadratic formula
-b±sqrt(b^2 -4ac)
----------------------
2a
-(-2) ± sqrt(2^2 - 4(1)(-2))
-------------------------------
2(1)
2 ± sqrt(4+8)
------------------
2
2±sqrt(12)
---------------
2
2±2sqrt(3)
----------------
2
1±sqrt(3)
roots: 2.73, and -.73
A.)

Use the identities

and

on the left-hand side

Make 1 have a common denominator to allow for fraction subtraction
Multiply the numerator and denominator of 1 by cos^2 x

Use Pythagorean identity for the numerator.
If

then subtracting both sides by

yields

. We can substitute that into the numerator

======
b.)

For the left-hand side:
By definition,

and

Since

Using Pythagorean identity,

so
2x²-6x+8=0
x²-3x+4=0
D=b²-4ac=9-16=-7
x=(3+/-i√7)/2
correct answer is the last one