Answer:

Step-by-step explanation:
First, look at the graph to determine whether it opens down or up, which in this case is <em>down</em>, so you insert a negative in front of the expression. Next, locate your <em>x-intercepts</em> [<em>zeros</em> (where the graph insects the x-axis)]. You will see that the graph intersects
and
so what you do is insert the zeros' OPPOCITES into the equation because according to the vertex equation,
that negative in front of
gives you the OPPOCITE outcome, so be careful.
I am joyous to assist you at any time.
Given : tan 235 = 2 tan 20 + tan 215
To Find : prove that
Solution:
tan 235 = 2 tan 20 + tan 215
Tan x = Tan (180 + x)
tan 235 = tan ( 180 + 55) = tan55
tan 215 = tan (180 + 35) = tan 35
=> tan 55 = 2tan 20 + tan 35
55 = 20 + 35
=> 20 = 55 - 35
taking Tan both sides
=> Tan 20 = Tan ( 55 - 35)
=> Tan 20 = (Tan55 - Tan35) /(1 + Tan55 . Tan35)
Tan35 = Cot55 = 1/tan55 => Tan55 . Tan35 =1
=> Tan 20 = (Tan 55 - Tan 35) /(1 + 1)
=> Tan 20 = (Tan 55 - Tan 35) /2
=> 2 Tan 20 = Tan 55 - Tan 35
=> 2 Tan 20 + Tan 35 = Tan 55
=> tan 55 = 2tan 20 + tan 35
=> tan 235 = 2tan 20 + tan 215
QED
Hence Proved
Answer:
(3,-21)
Step-by-step explanation: