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Geometry Level 2

If $\angle CAB =70^\circ$ , and side $b$ is 3 cm, what is side $a$ (in cm) rounded to the nearest integer?

Note : This triangle is not drawn to scale.

3 solutions

Krishna Karthik
Dec 3, 2018

simple trig. Tan(70 degrees)*3=8

A Former Brilliant Member
Sep 19, 2017

$\tan~70=\dfrac{a}{3}$

$a=3 \tan~70 \approx$ $\color{#D61F06}\boxed{8}$

Finn C
Jun 19, 2016

Given that we know $\angle$ CAB = $70^{\circ}$ , and side $b$ = 3 cm, using our trigonometric skills, we can determine $a$ .

With our limited knowledge of the opposite angle, and one of the legs of the triangle, we need to use $\tan$ to figure out the answer.

3 cm $\tan$ ( $70^{\circ}$ = 8.24...

8.24 rounded = $\boxed{8}$

How do you determine what $\tan 70^\circ$ is equal to?

How do you determine $\tan 70^\circ\approx8$ ?

A Former Brilliant Member - 4 years, 12 months ago

tan 70 is not 8 it is 2.74...
And for that I used the sine table

Harshit Mittal - 4 years, 11 months ago

You multiply it by three...

Finn C - 2 years, 6 months ago

I used a calculator... :D

Finn C - 4 years, 12 months ago

There are approximation methods that calculators use and algorithms that we can use.

Krishna Karthik - 2 years, 6 months ago