Section 3 (Rt.Triangle Trig.)
Nov 6th, 2010 by corricelli
Let’s use this page to post questions/concerns about Chapter 4, Section 3!
Happy blogging,
Mrs. Corricelli
15 Responses to “Section 3 (Rt.Triangle Trig.)”
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For number 29 on tonights homework I understand how to find the side legthns but how do you determine the angle sizes?
Colleen,
If adj/hyp = 1, then adj=opp. This has to be a Right Isosceles Triangle; aka 45-45-90.
Take care,
Mrs. Corricelli
hey guys, i forgot how to plug a degree sign in my calculator, remind me?
Colleen,
if you know that the side lengths are 1,1, sqrt(2), then you know that it is an isosceles triangle, and it has to be 45-45-90. then you know that theta = 45 degrees, or pi/4 radians.
Michaela,
to get the degree sign, hit 2nd apps (which is really angle), and the degree symbol is #1. to get the foot ‘ , hit 2nd apps (again which is angle), and it is #2. to get the ” , hit alpha plus (+).
Does anyone know what sort of answer number 37 is looking for? I couldn’t tell… Thanks!
Evan,
37 is a proof. The answer is given in the question; you have to show how one side LEADS to the other.
To start, remember (a+b)(a-b)=a^2 – b^2. Then use identities that Brian described in his post.
Take care,
Mrs. Corricelli
evan- use the fundamental trig identities diagram in the book on page 302 to help. you want to substitute tanO with sinO/cosO and substitute cotO with cosO/sinO. multiply (sinO/cosO)(cosO/sinO) to find your answer. hope this helps
michaela, to enter a number in degrees on your calculator, enter the number and then hit 2nd apps and its the first one there.
can anyone explain to me why sin θ = 1/2 = 30°? it’s on p. 304 in the book, example 8, and exercise 69 on the hw is almost the same.
Will,
Careful here. sin(theta)=1/2 means theta = 30 degrees NOT sin(theta).
69 is exactly the same; it absolutely employs this relationship. Good for you!
Take care,
Mrs. Corricelli
Does anyone know how to solve number 45?
Callum,
This is a LOT like the proof done in class. Look to get a common denominator.
Take care,
Mrs. Corricelli
Evan,
I think number 37 just wants you to prove that tan x cot=1.
It makes it easier if you substitute what tan(opp/adj) and cot(adj/opp) into the equation.
Colin/Even:
I would be careful about the opp/adj and instead use the identities as given in the book (as Brian mentioned), like tan(theta)=[sin(theta)]/[cos(theta)].
Also, Colin – watch cot; it needs to be cot of some angle measure; cot by itself does not make sense.
Happy blogging,
Mrs. Corricelli
for 41-45, what is it asking us to do? is it telling us to switch the functions or prove that they are equal or something?
and this might not pertain to this section (or this unit in general) but angle of elevation= angle of depression, given that it’s a right triangle.