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Trig Questions (1 Viewer)

bujolover

Active Member
Joined
Jan 5, 2017
Messages
154
Gender
Undisclosed
HSC
2018
Hi guys,
Could you please confirm for me that the given answers to the following questions are incorrect, based on their given working? I strongly believe that they're wrong, but I want to be certain. c:

Q1. Trig Question Working.PNG - Is the correct answer cotx?

Q2. If sinx = 2/√7 and cosx<0, find the exact value of tanx.

Find Exact Value of tanx Question.PNG - Given working. Shouldn't it be -(2√3)/3?

Q3. From the top of a lighthouse 70m above sea level, the angles of depression of two buoys due north of the lighthouse are 60 deg. and 25 deg. respectively. Find the distance between the two buoys. (Answer in 2 dec. pl.)

Lighthouse Trig Question Working.PNG - Shouldn't it be 109.70m (2 dec. pl.)?

Q4. Highlighted questions => From a Point A... Trig Question.PNG

Given working: From a Point A... Trig Question Working.PNG - Shouldn't it be for (iii), BQ = htan79°, and for (iv), h = 108m (nearest m)?

Thanks in advance! :)

P.S. Please don't feel like you need to answer all the questions at once. Any help is help! :)
 

InteGrand

Well-Known Member
Joined
Dec 11, 2014
Messages
6,111
Gender
Male
HSC
N/A
Hi guys,
Could you please confirm for me that the given answers to the following questions are incorrect, based on their given working? I strongly believe that they're wrong, but I want to be certain. c:

Q1. View attachment 33900 - Is the correct answer cotx?

Q2. If sinx = 2/√7 and cosx<0, find the exact value of tanx.

View attachment 33901 - Given working. Shouldn't it be -(2√3)/3?

Q3. From the top of a lighthouse 70m above sea level, the angles of depression of two buoys due north of the lighthouse are 60 deg. and 25 deg. respectively. Find the distance between the two buoys. (Answer in 2 dec. pl.)

View attachment 33897 - Shouldn't it be 109.70m (2 dec. pl.)?

Q4. Highlighted questions => View attachment 33898

Given working: View attachment 33899 - Shouldn't it be for (iii), BQ = htan79°, and for (iv), h = 108m (nearest m)?

Thanks in advance! :)

P.S. Please don't feel like you need to answer all the questions at once. Any help is help! :)
Q1 answer is cot(x). The solutions wrote tan(x) in line 3, but they had cos(x)/sin(x) before that, which is cot(x), not tan(x).
 

jathu123

Active Member
Joined
Apr 21, 2015
Messages
356
Location
Sydney
Gender
Male
HSC
2017
Hi guys,
Could you please confirm for me that the given answers to the following questions are incorrect, based on their given working? I strongly believe that they're wrong, but I want to be certain. c:

Q1. View attachment 33900 - Is the correct answer cotx?

Q2. If sinx = 2/√7 and cosx<0, find the exact value of tanx.

View attachment 33901 - Given working. Shouldn't it be -(2√3)/3?

Q3. From the top of a lighthouse 70m above sea level, the angles of depression of two buoys due north of the lighthouse are 60 deg. and 25 deg. respectively. Find the distance between the two buoys. (Answer in 2 dec. pl.)

View attachment 33897 - Shouldn't it be 109.70m (2 dec. pl.)?

Q4. Highlighted questions => View attachment 33898

Given working: View attachment 33899 - Shouldn't it be for (iii), BQ = htan79°, and for (iv), h = 108m (nearest m)?

Thanks in advance! :)

P.S. Please don't feel like you need to answer all the questions at once. Any help is help! :)
2. Yes, it should be -(2√3)/3
3. Yes, it should be 109.70m
4. You are correct for both parts, they are indeed htan79 and 108m
 

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