Math Is Fun Forum

simonmagusflies

Member

Registered: 2021-05-23

Posts: 32

Missing triangle angles

A right triangle has a 90 degree angle, and an angle x. What will the measure of the third angle be?

I answered 45 degrees, but the teacher said: "The angles are not 45 degrees because they are not necessarily equal to each other." There are a bunch of things it could be, then, but what's the "definitive" answer? Thanks.

Last edited by simonmagusflies (2021-06-21 15:48:21)

Bob

Administrator

Registered: 2010-06-20

Posts: 10,627

Re: Missing triangle angles

hi simonmagusflies

If x = 30, then the third angle is 180 - 90 - 30 = 60

So I think you do the same but with x rather than 30.

Get an algebraic expression and simplify it.

Check that when you replace x by 30, you get the answer above.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

buttdutt123450

Member

Registered: 2021-07-01

Posts: 1

Re: Missing triangle angles

Hi,
Actually, the angles would be 90, x and 90-x. 180-90 ( the right angle) gives 90. Therefore the other 2 angles add up to 90. If one of them is X, the other would be 90-x.

Mark Dater

Member

Registered: 2021-07-23

Posts: 12

Re: Missing triangle angles

you can immediately see that the angle will be 90