# How do you solve the triangle given #a=1.42, b=0.75, c=1.25#?

##### 1 Answer

A = 86.68

B = 31.82

C = 61.5

(2dp)

#### Explanation:

Just to clarify,

1st step : Get your calculator!

2nd step : Let's start by working out the angle

Let's substitute the known values :

3rd step : At this point, you will *probably* need a calculator. Ok, let's simplify this. With my calculator, I got :

4th step : So right now,

We need to get *inverse cosine* of

Let's just round that to 2 decimal places : 86.68

Next, let's work out side B. Although you can solve this using sine, since you asked us about using the Law of Cosine, I will use the Law of Cosine.

Substitute known values :

Plug in numbers on your calculator

Take the inverse cosine of that :

Round it to 2 decimal places : 31.82

Ok, so because interior angles add up to 180 in a triangle, let's set this equation for the last angle :

I'll leave it for you to check angle C using the Law of Cosines.