Present Perfect / Present Simple

[MiaL]

Hi,

I would like to know whether there is a rule about using the Presetnt Perfect / the Past Simple:
Examples:
- I (have) decided to write a letter to my grandmother.
- I (have) heard that you like tripe.

Thank you for your answer,

Mia

[Tdol]

The basic difference is that the present perfect is connected somehow to the present, so if I say 'I have heard' it is likely that I have learned this recently or that I am passing the information on to you now for the first time.

[MiaL]

So if I am writing a letter, which tense do I use?
-I've decided to write a letter to you? and I've heard that you like ...?

[hector51]

So if I am writing a letter, which tense do I use?
-I've decided to write a letter to you? and I've heard that you like ...?

plz give me the context,because these 2 sentences above are both ok!!

[MiaL]

Context:

Dear Grandma,

I've decided to write this letter because I haven't heard from you for a long time.
.....................................
I've heard that you have a new cat. What colour is it?
..
..
Is it correct?

[Tdol]

They're correct.