Let the unknown angle be x.
That is
sin x = 4/5
cos x = 3/5
By drawing a right triangle in the first quadrant,
hypotenuse = 5
Adjacent side = 3
opposite side = 4
That is tan x = 4/3
From the calculator,
x = arctan(4/3) = 53 deg (nearest integer)
Answer: 53 deg. (nearest integer)
Answer:
b. -x^2 + 50 = 25
c. |2x| = 10
d. x < 0
e. 2x < 10
Step-by-step explanation:
x = -5
-(-5)² + 50
-25 + 50 = 25
|2(-5)| = |-10| = 10
-5 < 0
2(-5) = -10 < 10
Answer:
a = 2, b = -9, c = 3
Step-by-step explanation:
Replacing x, y values of the points in the equation y = a*x^2 + b*x +c give the following:
(-1,14)
14 = a*(-1)^2 + b*(-1) + c
(2,-7)
-7 = a*2^2 + b*2 + c
(5, 8)
8 = a*5^2 + b*5 + c
Rearranging:
a - b + c = 14
4*a + 2*b + c = -7
25*a + 5*b + c = 8
This is a linear system of equations with 3 equations and 3 unknows. In matrix notation the system is A*x = b whith:
A =
1 -1 1
4 2 1
25 5 1
x =
a
b
c
b =
14
-7
8
Solving A*x = b gives x = Inv(A)*b, where Inv(A) is the inverse matrix of A. From calculation software (I used Excel) you get:
inv(A) =
0.055555556 -0.111111111 0.055555556
-0.388888889 0.444444444 -0.055555556
0.555555556 0.555555556 -0.111111111
inv(A)*b
2
-9
3
So, a = 2, b = -9, c = 3
