Skip to Main Content

Mathematics: Find an unknown angle measure

FIND AN UNKNOWN ANGLE MEASURE

In this module, you can study how to use trig ratios (sine, cosine and tangent) to find an unknown side length or unknown angle measure in a right triangle.

 

Did you know?

To find the unknown angle measure, you have to use 'inverse' sine, cosine or tangent.

These are the buttons on your calculator:               

(You may need to press 'SHIFT' first to get these.)

 

A 'TOA' example from the second video:

  • Unknown angle of a triangle
  • Opposite side of 3cm
  • Adjacent side of 4cm

 

On a calculator, type:

        SHIFT     tan       ( 3 / 4 )     =

 

On a different calculator, you may type:

       SHIFT    tan      ( 3 ÷ 4 )     =

or                        ( 3 ÷ 4 )     =

 

The answer you should get is:  36.9


Study and practice

TRIG FUNCTONS ON A SCIENTIFIC CALCULATOR

ONLINE SCIENTIFIC CALCULATOR

UCOL is part of Te Pūkenga - New Zealand Institute of Skills and Technology Learn More

Learn with purpose

Explore Te Pūkenga

Te Kāwanatanga o Aotearoa - New Zealand Government

Te Kāwanatanga o Aotearoa - New Zealand Government

Copyright © 2022 UCOL