### Home > INT2 > Chapter 10 > Lesson 10.1.3 > Problem10-38

10-38.

In $∆ABC$, $m∠C = 90°$, $AB = 10$ cm, and $\sin(A) = 0.5$. Without using a calculator, determine exact values for the following measures or ratios.

1. $m∠A$

Refer to the Math Notes box from lesson 4.2.4 for help with inverse trigonometry.
You may want to solve part (b) before part (a).

$30°$

1. $BC$

$\text{Substitute }0.5 \text{ for sin}A \text{ in sin}A=\frac{BC}{10}.$

Then solve for $BC$.

1. $\cos(B)$

See hint for part (a).

1. $AC$

Use the information given and answer (c) to solve for $AC$ using the Pythagorean Theorem.