Homework Help: trig

Posted by Paul C on Sunday, November 26, 2006 at 6:30pm.

Reduce the following to the sine or cosine of one angle:
(i) sin145*cos75 - cos145*sin75
(ii) cos35*cos15 - sin35*sin15

Use the formulae:

sin(a+b)= sin(a) cos(b) + cos(a)sin(b)

and

cos(a+b)= cos(a)cos(b) - sin(a)sin)(b)

(1)The quantity = sin(145-75)
= sin 70
= cos 20
note that If a+b=90 degrees then
sin a = cos b
(2) The quantity = cos (35 + 15)
= cos 50
= sin 40

No one has answered this question yet.

Answer this Question

Related Questions

Math sin/cos - On a piece of paper draw and label a right triangle using the ...
MATH - 1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL ...
Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 &...
Trig - Solve in terms of sine and cosine: sec(x) csc(x)- sec(x) sin(x) so far I ...
Math - calculus help needed example: sin-1(-1/2) how do you figure this out? The...
math - Can anyone help w/ these. 1) Solve the equation in the internal [0deg, ...
trig - Expan each of the following using the compound-angle formulae:sin(x + ...
Trig - In ABC, vertex C is a right angle. Which trigonometric ratio has the same...
maths - Choose the two options which are true for all values of x 1) cos (x) = ...
Math 2nd question - Express as a single sine or cosine function (note: this is ...

For Further Reading

First Name:
School Subject:
Answer: