For α = 7 π , which of the following hold(s) good?

(A) 3 α = 2 α + α ⇒ tan 3 α = tan ( 2 α + α ) ⇒ tan 3 α − tan 2 α − tan α = tan α tan 2 α tan 3 α (B) RHS = s i n 2 α s i n 4 α s i n 4 α + s i n 2 α = s i n 2 α s i n 4 α 2 s i n 3 α c o s α = s i n 7 2 π s i n 7 4 π 2 s i n 7 3 π c o s 7 π = s i n α 1 (C) cos 7 π − cos 7 2 π + cos 7 3 π = 2 1 (D) 8 cos α cos 2 α cos 4 α = − 1 , so D is false

Start Free Mock LoginAlready registered? Login here

Mathematics - Trigonometric Ratios & Identities Question with Solution | TestHub

MathematicsTrigonometric Ratios & IdentitiesMiscellaneous/MixedMedium2 minQB

MathematicsMediummultiple choice

For $α = \frac{π}{7}$ , which of the following hold(s) good?

Options:(select one or more)

Answer:

A, B, C

Solution:

(A) $3 α = 2 α + α \Rightarrow tan 3 α = tan (2 α + α) \Rightarrow tan 3 α - tan 2 α - tan α = tan α tan 2 α tan 3 α$

(B) RHS $= \frac{s i n 4 α + s i n 2 α}{s i n 2 α s i n 4 α} = \frac{2 s i n 3 α c o s α}{s i n 2 α s i n 4 α} = \frac{2 s i n \frac{3 π}{7} c o s \frac{π}{7}}{s i n \frac{2 π}{7} s i n \frac{4 π}{7}} = \frac{1}{s i n α}$

(D) $8 cos α cos 2 α cos 4 α = - 1$ , so D is false

Stream:JEESubject:MathematicsTopic:Trigonometric Ratios & IdentitiesSubtopic:Miscellaneous/Mixed

⏱ 2mℹ️ Source: QB

Doubts & Discussion

Loading discussions...