# Missing angle, Tan Theta?

1. Oct 9, 2011

### Haroldingo

1. The problem statement, all variables and given/known data

Ok, so this is really basic and i could do it at the snap of a finger liek a year ago but it's completely escaped me. Maths is too much.

This is a right angle triangle, with the right angle on angle C. Angles are marked A, B and C. Side CB = Adjacent, Side BA = Hyp and side CA = opposite.

A smaller triangle is sat with it's hypotenuse as side CA. It's a right angle triangle with D as the right angle, which sits on a line that travels from C to directly over A.

a) Calculate size of angle BAC.

b) Calulate length of DA.

2. Relevant equations

AB = 22cm
AC = 10cm

3. The attempt at a solution

I'm stuck. It's a simple bit of knowledge I've forgotten.

Something to do with Sineθ ?

Last edited: Oct 9, 2011
2. Oct 9, 2011

### Staff: Mentor

If C is the right angle, then the hypotenuse can't be CB.

The sides of the triangle would have to be AC and BC, and the hypotenuse would be AB.

Please give us the correct problem description.

3. Oct 9, 2011

### Haroldingo

Oh crap, I'm sorry!

CB is the adjacent and angle AB is the Hypotenuse.

4. Oct 9, 2011

### Staff: Mentor

Does this change affect anything else in your problem description? If so, please edit your original post to correct anything that might be wrong. You can edit your post by clicking the Edit button.

5. Oct 9, 2011

### Haroldingo

No, I don't think it should - I've edited whatever it may have effected

6. Oct 9, 2011

### Staff: Mentor

Your description still doesn't make sense to me.
The hypotenuse of the smaller triangle is CA on the larger triangle. Where is point D? It can't be on line segment CA, since that's the hypotenuse (of the smaller triangle). Angle D has to be across from the hypotenuse.

If you can draw a picture of the two triangles, and label each angle, that would be helpful.

7. Oct 9, 2011

### HallsofIvy

Staff Emeritus
Do you understand that the "hypotenuse" of a right triangle is the side opposite the right angle. "angle AB is the Hypotenuse" is impossible.

8. Oct 9, 2011

### Staff: Mentor

The OP meant side AB, but I am still not able to get a clear picture from his/her description.