help please please anyone ?
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Answer:
Step-by-step explanation:
Cos 135°=cos(180°-45°)= -cos45°
Explanation:
Cos 135° is an angle in the second quadrant.
In the second quadrant, cos is negative.
cos
θ
=
x
r
cos
135
=
cos
(
180
−
45
)
=
−
cos
45
°
An angle of
45
°
is found in a right-angled triangle of sides
1
:
1
:
√
2
cos
45
°
=
1
√
2
∴
cos
135
°
=
−
cos
45
°
=
−
1
√
2
Note that
√
2
is an irrational number and cannot be given as an exact decimal.
Answers : (1)
sin x = sin (π – x)
sin 135 = sin (180 – 135) = sin 45 = 1/sqroot(2)
We can also solve this by using the sin (90 + 45)
To find evry angles, we only need to see its combination either in summation form or product form of the angles we know like 30, 45, 60 and 90.
Good Luck!
Thanks & Regards
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