# I am having trouble solving this Hinge Theorem Geometry proof. I understand the Hinge Theorem, but how is m<1 congruent to m<2?

##### 1 Answer

Jan 26, 2018

Please see below.

#### Explanation:

We can use cosine formula for triangles.

We have

also

and as both angles are less than

Now using cosine formula in

**..................(A)**

and in

**..................(B)**

Compare RHS of (A) and (B),

we have

i.e.