Question

solve sin^2+cos^2=1​

Answer 1

1)

s
i
n
v
=
b
c

b
=
c
·
s
i
n
v

2)

c
o
s
v
=
a
c

a
=
c
·
c
o
s
v

Lets use 1) and 2) in the pythagoreans theorem instead of
a
and
b
.

(
c
·
c
o
s
v
)
2
+
(
c
·
s
i
n
v
)
2
=
c
2

Expand the two parenthesis

c
2
·
c
o
s
2
v
+
c
2
·
s
i
n
2
v
=
c
2

Divide each term on both sides by
c
2




c
2
·
c
o
s
2
v
c
2
+
c
2
·
s
i
n
2
v
c
2
=
c
2
c
2

c
o
s
2
v
+
s
i
n
2
v
=
1

And we are done with the proof!