Complicated Math Equation

Home Schooling: Week One

It started, and ended, with a roll of the teenager’s eyes, and one sum. 

“Who calls it a sum, anyway? It’s an equation, Mum.’’

I’ve got this, I retorted.  Year 10 Maths. That confidence – along with the brand new school bell I’d purchased just before self-isolating – would have me respected, revered even, and being called Ma’am, before morning tea. 

An isosceles triangle is constructed with equal sides of 15cm and an obtuse angle of 120 degrees. Determine the size of the third side and the other two angles.

I stared at it. Isosceles. Isosceles. I remembered the word, but thought it might have been the surname of a lad I dated in the 1980s, at Queensland University.

Just a tick, I said buying time. I think that’s a work call I need to take.

Out of the bar, temporarily (emphasis on that temporarily) declared a school room, up the stairs, and onto my computer.

Google. ISOSCELES DEFINITION, I typed. And there it was.

“In geometry, the word isosceles describes a triangle with two sides that are the exact same length. The angles across from each equal side are also the same in an isosceles triangle.’’

Voila. I’ve got it I said, repeating the definition. “No Sugar Sherlock,’’ came the response. “I know what it is. But how do I determine the size of the third side and the other two angles?’’

Oh, is that what you wanted? No problem. I’ll be back in a moment.

Google. “How do I determine the size of the third side and the other two angles of an isosceles triangle?’’

Google, no matter what the politicians say, can be a godsend. Something called the “cosine formula’’ gave “the square on a side opposite an angle, knowing the angle between the other two known sides’’.

Back down the stairs, and into that temporary class room. I should move those bottles of sauvignon blanc, I thought, very briefly. 

I’ve got it, I declared. You see Sweetie, it comes down to the Cosine Formula. With every part of my being, I tried not to sound too self-congratulatory.  

I adore her smile. Sometimes it a smirk, but this was a full-on Cheshire grin that teenagers don’t give out too freely. It spread from one ear to the other.

“Really, Mum. That’s superb! Is that the same as Cos?’’

That bloody work phone. I heard it again. Back up the stairs, and to the computer.  This time I saved time. It seems the more you type “Google’’, the more it pops up just as you type G.

“Is the Cosine Formula the same as COS?’’ 

Yes. Yes. Yes. There was the answer in black and white in front of me. Thanks Sir Google. “The cosine function, along with sine and tangent, is one of the three most common trigonometric functions. In a formula, it is written simply as ‘cos’.’’

Back down the stairs. I really should remove that sauvignon blanc, I thought. It’s a bad look, even in a temporary classroom. 

Yes, I told her excitedly. You are right.  Cos = Cosine!  Now I was grinning like that cat.

Don’t be smug, I told myself. Now that wasn’t too hard was it, Sweetie?

“So what’s the answer then?’’ Her question carried a giggle.

My pretence was over, and we both knew it. She’d done the sum, opps equation, and was having the first day’s laugh, at my expense.

I left that temporary classroom, and took the bottle of sauvignon blanc with me. It really was a bad look, for it to be sitting there each day.

This column may or may not be true but is a reminder that teaching is best left to teachers!

Photograph of Madonna King

Madonna King is a leading journalist and commentator. An award-winning presenter of 612 ABC Brisbane, she has authored 12 books and now works across radio, television and online.

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