Can-anyone-please-resolve-the-Q-159787-in-details-

Question Number 159973 by abdullah_ff last updated on 23/Nov/21

C a n a n y o n e p l e a s e r e s o l v e t h e

Q 159787 i n d e t a i l s . .

Commented by tounghoungko last updated on 23/Nov/21

y o u r q u e s t i o n h a d s o l v e d b y

c o r t a n o s i r . w h y y o u a s k a g a i n ?

Commented by abdullah_ff last updated on 23/Nov/21

Here is the question :

if {c o s}^{4} θ - {s i n}^{4} θ = 2 - 5 c o s θ

then find the value of θ

Commented by Rasheed.Sindhi last updated on 23/Nov/21

{c o s}^{4} θ - {s i n}^{4} θ = 2 - 5 c o s θ

({c o s}^{2} θ - {s i n}^{2} θ) ({c o s}^{2} θ + {s i n}^{2} θ) = 2 - 5 c o s θ

({c o s}^{2} θ - {s i n}^{2} θ) (1) = 2 - 5 c o s θ

{c o s}^{2} θ - (1 - {c o s}^{2} θ) = 2 - 5 c o s θ

2 {c o s}^{2} θ + 5 c o s θ - 3 = 0

2 {c o s}^{2} θ + 6 c o s θ - c o s θ - 3 = 0

2 c o s θ (c o s θ + 3) - 1 (c o s θ + 3) = 0

(2 c o s θ - 1) (c o s θ + 3) = 0

2 c o s θ - 1 = 0 \lor c o s θ + 3 = 0

c o s θ = \frac{1}{2} \lor c o s θ = - 3 (f a l s e)

θ = \pm \frac{π}{3} + 2 k π; k \in Z

Commented by abdullah_ff last updated on 23/Nov/21

t h a n X S i R

Commented by Rasheed.Sindhi last updated on 23/Nov/21

H e w a n t e d t h e a n s w e r i n d e t a i l .

Commented by abdullah_ff last updated on 23/Nov/21

Dear tounghoungko sir,

as Rasheed . Sindhi sir said, I w a n t e d

t o k n o w t h e s o l v e o f t h e q u e s t i o n i n

d e t a i l . So, I asked to resolve it .

B u t a l s o t h a n k s t o cortano s i r f o r

h i s e f f o r t a n d t o h e l p i n g m e .