Question

help please please anyone ?

Answer 1

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!

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