Answer :
Answer:
5π/6
Step-by-step explanation:
Given :
- cos⁻¹ (cos7π/6)
Solving :
- We know that : cos⁻¹ cosθ = θ
- But we can't just do that in this case
- Because the range of cos values is [0, π]
- Clearly, our value does not lie in this range
- We have to take a different Quadrant other than the 3rd Quadrant which gives cos a negative value
- The 2nd Quadrant also has cos values negative
- Therefore,
- cos⁻¹ cos (π - π/6)
- cos⁻¹ cos (5π/6)
- ⇒ 5π/6 ∈ [0, π] ⇒ It lies in the range!
Answer:
5π Over 6
Step-by-step explanation:
You can write 7π6 as (π+π6)Thus we can clearly see the angle falls in the third quadrant. And the cosine value in third quadrant is always negative. Hence, cos(π+π6)=−cos(π6)coming back to the question cos−1[cos(7π6)]=cos−1[−cos(π6)]=π−cos−1[cos(π6)]=π−π6=5π6