Using the figure to the right, if RSTU is a rhombus, find measure RST.

Given:

In rhombus RSTU, and .

To find:

The .

Solution:

We know that, diagonals of a rhombus are angle bisector. So,

Isolating variable terms, we get

Divide both sides by 7.

Now,

And,

.

Now,

We know that opposite angles of a rhombus are equal.

Therefore, the measure of angle RST is .