# In triangle ABC, <B is a right angle and m<A = 40. Given that AC = 15, what is AB to the nearest tenth?

Apr 4, 2018

11.5. See below.

#### Explanation:

I think this is what you mean, see diagram below:

You can use the definition of cosine.

$\cos \theta = \frac{a \mathrm{dj} a c e n t}{h y p o t e \nu s e}$

$\cos 40 = \frac{A B}{15}$

so ,
$A B = 15 \cos 40$

$\cos 40 = 0.766$

 AB = 15 * 0.766 = 11.49 = ~ 11.5 to nearest tenth.