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System Message

[00:00:00] *** Please note: All sessions are recorded for quality control. ***

Greg (Customer)

[00:00:01] Help prove a trig identity. sinx-siny = 2cos([x+y]/2)sin([x+y]/2)

Roberto C (Tutor)

[00:00:07] Welcome to Tutor.com !
Let's get started.

Greg (Customer)

[00:00:20] Can you help me prove this
trig identity?

Roberto C (Tutor)

[00:00:35] We can try! what properties have you learned so far?

Greg (Customer)

[00:00:48] I think most of them.

Roberto C (Tutor)

[00:01:18] I'm researching...

Greg (Customer)

[00:01:47] ok

Roberto C (Tutor)

[00:03:05] Okay I'm pretty lost here. I won't waste any more of your time. I can transfer you to someone who will be able to help you much more if you'd like!?

Greg (Customer)

[00:03:12] sure

System Message

[00:04:25] *** The session has been transferred. ***

Max W (Tutor)

[00:04:36] Welcome to Tutor.com !
Let's get started.

Greg (Customer)

[00:05:14] ok

[00:05:26] can you help me prove this
trig identity?

Max W (Tutor)

[00:05:50] i would start with the right hand side

[00:07:08] we can use the double angle formula for sine here

Greg (Customer)

[00:07:11] ok

Max W (Tutor)

[00:08:53] then we use the sine of the sum formula

Greg (Customer)

[00:08:50] how does 2cos(x+y/2)....
equal sin(x+y)?

Max W (Tutor)

[00:10:01] review your double angle formula for sine but read it from right to left

[00:10:11] i have written it in light blue

[00:10:28] here A = (X+Y)/2

Greg (Customer)

[00:10:25] is sin2a part of the black
equation?

Max W (Tutor)

[00:10:39] no

[00:11:49] registering now?

Greg (Customer)

[00:11:52] yes

Max W (Tutor)

[00:12:02] cool

[00:12:38] cosine of X is sine of (90 - X), right?

Greg (Customer)

[00:12:45] yes

[00:14:56] ok

[00:16:01] where would i go from here?

Max W (Tutor)

[00:16:30] i am thinking for a second

[00:18:01] I'm working on this...